October, 1 1924 15 Cents a Copy

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IN THIS ISSUE: How and Why of a Radio Filter Special Article by H. V. S. Taylor "C" Battery Lives on Hill Radio on Army World Flight Cutting Down the Losses Make a Good Cabinet for Your Radio

WATCH FOR OUR HOOK- UP NUMBER

YOU WILL UNDERSTAND THIS MAGAZINE ---AND WILL LIKE IT

PUBLISHED TWICE A MONTH pá á°a î î Ì î î î To Radio Dealers î îI and î î I Manufacturers I

îI HERE'S A CHANCE TO GET î BUSINESS î î Ì In response to many requests Radio Progress will issue a î î I î Spei-al Hoof -up Number î Ì î TO COME OUT IN THE NEAR FUTURE î I This is a carefully I ,elected list of sets which WILI. î WORK. They include the best hook-ups of Crystal Sets, Single Tubes, Regenerative and Non -Regenera- tive, Two and Three -tube Radios, Reflexes, Neutro - dynes and Superheterodynes.

1 This issue is bound to create a demand for parts and î sets. You should get some of this business. Rate card sent on request. î î ÌI Radio Progress îI î 8 Temple Street Providence, R. I. î î P. 0. Box 728 î î î

- ,11,-1 I I 1-1,-1 ) ) 1 1 I )

Le_e_e_e_e_e_e_2_era-c Q fl QQ-2-2-2.-A-2-11--Q.--(-c-c-c-c-c-c-c.... Dº6 l.) 1 l :1 ) ...... mm ) 11m And If I am Elected Just Watch Business Pick-up"

Which one of the candidates for President spoke these words over the radio? Are you getting the fun and the in- teresting information which is coming pretty regularly these days through the air to those who have crystal sets? If you are missing the enjoyment and entertainment which is furnished by the wonderful programs now being sent out by the big broadcasting stations, and particularly at this time of the year, if you don't hear the way your favorite candidate shows how the other two parties would wreck the country, then by all means invest $2.95 for a RADICLEAR Crystal Set With this outfit and a pair of phones you can pick up local broadcasting in a way which will delight you. The RADICLEAR Crystal set is unusual in that there are no sliding arms or handles to turn. This means that it is easy to operate and also that there is no loss through short circuiting of turns by the slider. As a result the speeches are unusually clear and loud. This set includes the famous Audion Crystal, which is alive all over. This is sold separately at 25e.

TAYLOR ELECTRIC CO. 1206 BROAD STREET

PROVIDENCE, R. I. Special Features for the October 15th issue of Radio Progress

A big sending station shoots music into the air. Do you know how it reaches your aerial? There are two paths by which the waves may reach you and sometimes one is better, and sometimes the 'other. See "RADIO WAVES THROUGH SKY AND GROUND," by Dr. Alfred N. Goldsmith in the next issue.

When you look at a variable condenser and see the plates turn around and around, doesn't it seem foolish that these can switch the music from New York to Chicago and from Chicago to San Fran- c'sco? How does it accomplish so much in such a little space? It is simple when you read about it in "HOW CAPACITY WORKS IN A CONDENSER," by Horace V. S. Taylor. Many fans have superheterodynes or are thinking of building this very popular set. Many articles have explained the detailed workings of the various parts, but it isn't everyone that can trace the path of the music through one tube after another, particularly when some of the tubes are reflex, as in the Radiola Model. A road map and description of the path of the program through 'the set will be given in "TRACING THE MUSIC THROUGH A SUPER - HET," by Oliver D. Arnold.

Are some of your friends good natured liars? If not, why is it that they can get so much more than you can with a cheaper appara- tus? Some pointers on getting the best out of your set and also hints on checking up to see whether your friends are speaking the truth will be found in "WITH A GRAIN OF SALT," by Harry A. Nickerson, in the October 15 issue of RADIO PROGRESS. RADIO PROGRESS

HORACE V. S. TAYLOR, EDITOR

Volume 1 Number 14

Contents for OCTOBER I, 1924

HOW AND WHY OF A RADIO FILTER 5

"C" BATTERY LIVES ON HILL 9

RADIO ON ARMY WORLD FLIGHT 13

FEEDING MUSIC TO THE AIR 15 CUTTING DOWN THE LOSSES 17

HIGH POWERED STATION WILL OPEN SOON 19

THIRD RADIO CONFERENCE COMING 20

BROADCASTING OVER PHANTOM LINE 21

EDITOR'S LOUD SPEAKER : THAT MESSAGE FROM MARS 23 TWO RADIO GAMES 23

MAKE A GOOD CABINET FOR YOUR RADIO 25

AMERICAN RADIO RELAY LEAGUE 27 SENDING STATION STORIES 28

DR. RADIO PRESCRIBES 29

1ROADOASTING STATIONS 31

RADIO Pnoon ss is issued on the 1st and 15th of each month by the Oxford Press at 8 Temple Street, Providence, Rhode Island. John F. O'Hara, Publisher. Yearly subscription in U. S. A., $3.00. Outside If. S. A., $3.50. Single copies, 15 cents. Entered as second-class matter, April 4, 1924, at the Post Office at Providence, R. I., under the Act of March 3, 1879. Address all communications to RADIO PROGRESS, R Temple Street (P. O. Box 728), Providence, R. I. Title registered at United States Patent Office.

The publishers of this magazine disclaim all responsibility for opinions or statements of contributors hich may at any time become subjects of controversy. STAND BY!

.. FOR .. Radio Progress Special Hook-up Number

TO BE ISSUED SOON

15 Worthwhile Hook-ups

Undoubtedly you have tried following various wiring diagrams and found that they were not what

they pretended to be. This ' will be a carefully selected list of sets which do work. They include the best hook-ups of crystal sets, single tubes, regenerative and non -regenerative, two and three tube radios, reflexes and also the more ambitious styles, like neutrodyne and superheterodyne. Among them you will find several, anyway, which you will wish to try out.

DON'T MISS THIS ISSUE RADIO PROGRESS " ALWAYS ABREAST OF THE TIMES "

Vol. 1, No. 14 OCTOBER 1, 1924 15e. PER COPY, $3 PER YEAR

How and Why of a Radio Filter They Smooth the Hum Out of Sending and Receiving

By HORACE V. S. TAYLOR

AGREAT deal is said these days about What the Commutator Does spring will absorb a lot of vibration omitting "A" and "B" batteries The commutator of a generator con- which would otherwise be carried to the from a receiving set. Of course, it is a -i;ts of a large number of copper bars, delicate mechanism of the clock. Such great advantage if these expensive and insulated by strips of mica, as shown in a way of protecting it removes almost troublesome units can be done away Fig, 1. As these rotate under the brushes all of the rapid vibrations which the with. Most of the schemes so far pro- which carry the current in and out of roving van causes. posed give pretty good results, except for the armature, there is a slight disturb- the fact that the hum, which is caused ance every time a bar leaves contact by the alternating current, is heard quite with the brush, and the constant pro- distinctly in the phones or loud speaker. cession of these ripples, one after the The whole idea of a filter as used in such other, causes a hum which is broadcast a device is to kill this hum. along with the music. It is the function Another place where a filter always of the filter to suppress this undesirable has to be used is the generator circuit noise. of a sending station. Generators are The two uses of this device which has used instead of batteries to supply the just been mentioned are for the purpose Fig. 2. Springs Absorb Shocks plate current for transmitting tubes, as of keeping a steady, direct current sup- the pressure is so high, several thousand plied to a device, rather than one which The clock is a rather light weight, and volts, that a tremendous number of cells fluctuates slightly. Still another use for so it will get some banging around even of "B" batteries would be required if a filter is in conditions where a certain when mounted on the spring as just these were used. Sometimes an "A" speed of vibration of alternating current shown. The small and very rapid oscil- battery is employed to light the fila- is desired in one circuit, but not in an- lations will be filtered out by the spring ments of the tubes, but since considerable other. For instance, a wave trap is a before they reach it, but the slower vi- money is tied up in batteries large form of filter. The differences between brations, which are perhaps stronger, it and the first kind mentioned is that on will still cause a lot of jouncing up OWN G and SNAGT direct current there is no particular down when the truck runs over a rough tuning needed, whereas, when used with place in the road. How can this be high frequency alternating current, it' avoided? The obvious way to do is to is necessary to tune the circuit to the put a heavy block of iron down on the particular wave length in question. springs of the bed and then place the Like Moving a Clock clock on top of it, as shown in Fig. 3. To show the general way a filter This mass of iron is, of course, quite works, we may refer to the analogy of heavy and it will not take up the bounc- cef£a /iAR transporting a clock on moving day. We ing and throwing about which the clock, have a very expensive timepiece Fig. 1. Cause of Sending Hum which owing to its light weight, was absorbing we are afraid to take on the moving van before. The combinations of the weight enough to run the big filaments of the with the rest of the goods for fear the of the iron and the spring of the bed sending tubes, it often is found best i o vibration may damage the works. As an makes an ideal arrangement to filter out use a generator for this purpose also. improvement on placing it in a bureau the vibration which would otherwise In either of these positions a generator draw, we can put it down on the mat- reach the pendulum of the timepiece. causes a certain amount of noise, owing tress and spring of a bed as shown in Notice here that there are two things to the so-called "commutator ripple." Fig. 2. This is quite a help, as the necessary to filter out the vibration, first 6 RADIO PROGRESS OCTOBER 1, 1924 the springs, which absorb the oscillations The way this instrument works is as and a weight, so when we get to the elec- easily, and second the weight, which re- follows: The roll of paper, being as trical circuit, there are two separate pels the vibration. It is only when these just explained, carried by the frame elements. The spring is represented by two elements are combined that the best which is solidly attached to the ground a condenser, while the weight is repro- results may be obtained. will naturally take up any vibrations duced in a form of a coil or inductance which the earth is having. If an earth- Just as the weight of the block of iron Filtering Out an Earthquake quake happens, then the paper will fluc- is measured in pounds, so the electrical The same principle is made use of in tuate violently up and down at the same weight of the 'coil is measured by its in- the apparatus which measures the form time it is slowly pulled along by the ductance. The unit of inductance is the and of an This strength earthquake. clock work. On the other hand the instrument, is called a seismograph, illus- spring and weight make up a filter IRON/3cock which removes all vibration from the pen point. The spring absorbs the vibra- tions and the weight repels them with the result that the pen is quiet in space without any motion at all. Since the paper is vibrating up and down, and the + i© + +I pen is not, the latter will leave a wavy ©,,e-+ zsno continuous line on the strip. LIN a. When no earthquake or other motion Fig. 5. Current from Rectifier of the ground is occurring then the pen Fig. 3. Weight Helps Spring will trace a perfectly straight line on millihenry. The combinaton of condenser and a coil acts as our trated in principle in Fig. 4. It consists the paper roll, but as soon as a tremor electrically just mechanical filter does; of a spiral spring which carries at its in the earth is felt, then the paper wig- that is, the con- lower end a heavy weight. The spring gles up and down and the stationary pen denser absorbs the electrical oscillations, is supported from the ceiling of the room leaves a very wavy line, as shown in and the inductance repels them. in which the apparatus is housed. At our diagram. Of course, the more Suppose we have a rectifier which we fila- one side of the weight is a pen point, severe the disturbance, the greater will want to use to supply current to the which bears against a strip of paper. be the height of the mountains which ment. If we ran a 110 volts A. C. In the actual construction, the pen is not show on the record. Since the motion through a transformer to step the poten- fastened directly to the weight, but is is magnified very greatly by the levers, tial down tp six volts, and then feed that to the tube, the shape of the current attached to it through a system of levers (which are not shown here) , it is pos- which magnifies the motion perhaps a sible with this instrument to detect an wave would look like the upper curve of hundred times. The strip of paper earthquake which may have occurred Fig. 5, that is, there will be a positive loop and then a negative loop. This means that if we put a volt meter across the terminals of the filament and the

CEILING- meter were sensitive enough to record RECORD OF such rapid changes, that the needle would first swing over six volts to the right and EA-zTNQuAKE Sp 1 RAL SpRING- an instant later six volts to the left. This happen 60 RA ° change back and forth would NH^ j, times every second. Of course, this would give a terrible hum in the telephones. The usual city current is 60 cycle fre- quency. But instead of connecting the second- PEN PO I rV T ary of the transformer right to the fila- ment, suppose we run it through a rec- NE 1G HT tifier, like a Tungar or a vibrating rec- tifier, or perhaps a chemical style, which uses two plates dipping in a solution of Fig. 4. An Earthquake Signs Its Name salts. If this instrument were the style against which a pen rests is unwound half way around the globe. The first which uses both half of the waves and slowly from a big roll and winds up on news of the Japanese earthquake was reverses the negative so as to add up with a drum, which is driven by clock work. received on a seismograph in Washing- the positive, then the curve would look like the lower of Fig. 5. If a quick The strip unwinds quite slowly so that ton, D. C., a few seconds after the event half across only a few inches pass every hour. The occurred. reading volt meter were connected paper rolls are carried on a framework What Makes an Electrical Filter the filament with this style, then the flicker violently from zero which is bolted securely to a strong ma- Just as in both these cases it was needle would sonry slab sunk deep in the ground. necessary to have two parts, a spring up to six, and then back to zero again. OCTOBER 1, 1924 RADIO PROGRESS 7

This would not be much better than be- rent which passes through the various weight. Just as the spring allowed the fore, because there would still be a ter- parts of the circuit. The two wires run- oscillations to pass and the weight pre- rible racket in the phones. ning to the left are connected to the rec- vented them, so in Fig. 7 the condenser tifier and those at the right go to the lets the ripple on top of the wave run What the Filter Does radio set. It will be observed that the right through from the upper to the As the next step let us assume that a upper line runs right through from the lower line in Fig. 7 and so it does not filter is cut into the circuit in the way rectifier to the radio. The condenser, pass through the radio set, while the coil which will be described in a minute. which is shown connecting the two lines acts like the weight and opposes any If this is a good filter, it will change the current to a fairly continuous flow, as shown in the upper part of Fig. 6. Here we have continuous current (as ZERO LINE shown by the waves being entirely above b o o the line) but on top of this steady cur- Cvn cfv,oezt. rent is a ripple. This resembles a river, nun which in calm weather will flow stead- v v vÿ TNRu ily toward the "sea, at say, three miles Fn-TER LARGE Cas. per hour. In rough weather, when a heavy wind is blowing, the river con- tinues to move with ,a speed of three miles toward the ocean, but on top of this the wind kicks up a lot of waves which may have a bigger effect than vvP the main flow of the current itself. INTO F/ L7' E R OUT of FAz.r Such a form of current when fed to « the tube will give pretty fair results, ZERO but some noise will still be heard. In LINE ZERO LINE order to reduce this further, we can do Fig. 7. Current In and Out of Filter either one of two things. One way will have a capacity of one or two mfd. wave motion or ,in other words repels it, is to connect a second filter in the Notice that this is on' thousand times while the direct current can pass through line and the other is to use a larger unit as big as the .001 mfd. which is in com- it quite easily. freni the first filter, that is, more plates mon use as a phone condenser and also This is illustrated by the curves which in the condenser and a larger number of for other purposes in the ordinary radio accompany the diagram. First look at turns on the winding of the coil. If we set. The reason for this large size is be- the lower left hand corner which shows make either one of these changes, then cause that while the radio condenser is the direct current coming from the rec- the wave on top of the direct current fed by a frequency of several hundred tifier or from another filter, showing a will be cut down very considerably, so thousand up to a million, the one in the very pronounced ripple in the direct cur- that the curve will look like the lower filter has to work on a frequency of only rent. This shows that if a volt meter hall' of Fig. 6. This is like our river 80 cycles per second, and this slow speed were connected to the filament terminals when the wind hits died down quite a requires a much larger capacity in order of the vacuum tube the needle would lot and the waves have dropped to mere to pass sufficient current. flicker back and forth between 4 and 6 The coil, which is shown connected in volts, changing from one to the other the lower line, is built on an iron core and back again very rapidly. This fluc- ZRO ILNf and will have several thousand turns. tuation would be heard in the phones as An ordinary audio transformer would a musical hum. Now remember that the have enough turns, but the wire in this condenser is like a spring. A spring will latter is so small, that it would burn easily vibrate back and forth and so the out in attempting to run one or two current through the condenser will vi- amperes through to light fila- ZanOIIN[ it the brate back and forth just as shown in ment. The wire for such a coil should the upper part of the sketch. You will Fig. 6. What the Filter Does be at least as large as No. 28 and should notice that it goes from plus one to ripples on the surface. If this still causes be larger if more than four tubes are to minus one ampere and lies on both sides too notch hun in the telephones, the be used in the set. of the line since direct current cannot go cure is to go farther with the treatment. through a condenser. In other words, the coil and condenser Cutting Out the A. C. Waves should be further increased in size. You will see that the filter is really a Only Small Ripple Through Coil very simple device, consisting only of the Now look at the shape of current wave What the Filter Looks Like condenser and coil. The condenser is just through the coil. Since it is like a heavy Fig. 7 shows a hookup for the filter, exactly like the spring that we showed weight it cannot be shaken back and and also the shape of the wave of cur- in Fig. 4, and the coil resembles the forth very fast (this shaking is not 8 RADIO PROGRESS OCTOBER 1, 1924

mechanical, but electrical it must be re- are better yet, then he will object to the The filter is connected just as it was in membered) . So the current, which it ripple which you do not notice. Of Fig. 7 with the supply at the left and the passes on to the set, will be in one di- course, if the hum is reduced to such a tubes at the right. The top connection rection only and will have only a very low value that we cannot hear it, then it runs direct from small ripple. As already explained in does no harm at all, even though we the rectifier to the Fig. 6 this will be so small that it prob- know it must be there still. tubes and in. the diagram the first fila- ably will cause no trouble in the tele- ment connection is purposely shown at Hooking Up phone. If it does, however, the remedy the Set the left of the condenser. This is to is to use a larger coil with the condenser. The scheme of connections for a filter illustrate the point that the output may It may seem from this description that is shown in Fig. 8. We have here two be taken off this line at any point. The condenser and coil play the same part P here that they did in Fig. 7, that is, the condenser passes or short circuits the of F F RMeo ripple on top the direct current while the coil repels this ripple and allows only a steady current to flow. It is this lat- T ter which lights the filaments of the tube. In using such a device it is well to place both condenser and coil at least a foot or more away from the radio set itself. This is to prevent the magnetic rROM action of the former from affecting the /QECilH/E2 FiLTER coils of the set. Doing Without a "B" Battery The same idea which is shown here Fig. 8. Applying Filter to Radio Set connected to the filaments of the tube it is not possible ever to get an abso- vacuum tubes, which may be detector and may be used on the plate circuit. The lutely smooth wave by using any number amplifier, or perhaps two steps of ampli- difference in construction will be this: of filters. As a matter of fact, this is the fication. The grid and plate circuits Whereas the filaments will take from one truth-we can never get a line which is are not shown since they may be used in to two amperes at a small voltage, say theoretically smooth. The best we can any kind of a set from a single circuit five or six, the plate, on the other hand, do is to reduce the hum to such a low squealer to a nine tube superheterodyne. requires 22 up to 90 volts and the cur- value that it does not bother us. If The filaments are shown connected each rent is very small, only a few thou- your ears are better than mine, then you with its separate rheostat although one sandths of an ampere (a few milliam- will need a larger filter to quiet the set might just as well serve the purpose of peres) . That is why the coil for use in than I will. But if John Smith's ears controlling both tubes at the same time. the plate circuit filter must be wound of a very large number of turns and since the current is small the wire may be No. 30. The condenser here will have to RADIO PROGRESS be insulated so that it can stand the full 8 Temple St. (P. 0. Box 728) Providence, R. 1. Date plate voltage, whereas in the former case a paper insulated unit that will with- stand six or eight volts is all that is re- You may enter my subscription to RADIO PROGRESS quired. f1 year $3.00 As a matter of fact, very many of year the schemes at present on the market for 2 years $5.50 for using no "B" batteries are built on Signature the principle of transformer to give the proper voltage, connected to a rectifier Send it to this address which makes pulsating direct current out of alternating and then a filter to strain Paid by (PRINT) off the ripple on top of the direct cur- Check rent. These devices are successful in overcoming the noise in the phones pro- Cash vided the filter is large enough. Of course, such units cost money, and the Money order tendency is to cut them down as small as can be used to give good results. ©eroLBR ,1,..1924. RADIO PROGRESS 9 "C" Battery Lives On Hill It Gives Out No Current But Is Quite Important

By OLIVER D. ARNOLD

T days of old a 22 -volt "B" battery the hill which is in front of their house. the boys of the "X" family enjoy a 1 was often all that was used to oper- Let us also assume that the children are smooth coast on the steep part of the ate the single tube sets which most fans obedient. hill? The only thing they can do is to owned. But in these enlightened times In such a case it is quite clear that change their location from the top to the it is not at all unusual to find 90 or even the "Y" boys will have the advantage middle of the hill. By moving down half 120 volts applied to the plates of the over the other two families. In the first way they strike the smooth part which amplifiers in a five to eight tube set. place the road opposite their hoúse is is also the steep part. The same thing When 22 volts was the total of the "B" smooth, whereas at the other two houses exactly applies to the radio tube. Unfor- pressure there was no advantage at all the highway department has carelessly tunately the ordinary amplifier happens in using more than two different batter- let the road become quite rough. The to work around point "X" when a large ies, the "A" and the "B". But with the pleasure of sliding at "Y" will for that advent of the high pressures on the reason be considerably greater than at s plate, it is very desirable to use a "C" either "X" or "Z". Besides, notice that 3 battery in addition to the other two. the hill is a good deal steeper at the 6W Many users and even builders of sets center than it is at the top or bottom fully the ad- and so the sliding will be a great deal do not seem to understand - E vantage of using a "C" battery. As more efficient there. d just explained there is no benefit from The conditions as represented in this z e using one on a set having only 22 volts diagram are just like what occurs in a GRID VoigoE of plate pressure. Even when 45 volts vacuum tube. The hill is represented by Fig. 2. Voltage Slides Down Hill are used it is doubtful whether this extra the "Characteristic Curve," which is the "B" battery voltage is applied. The disad- battery will be worth the increase in name given to the drawing showing the vantage is that we get distortion, owing complication from connecting it in the performance at the tube. Such a curve to the roughness or curvature of the line, set. When the plate voltage is run up Fig. 2. represents the amount of current and besides, the amplification is not as flowing through the plate (this is the great because the curve is not very steep RovoN output of the tube) compared with the at that point. To get better results we

DB voltage of the grid, (the input.) This is must take a leaf out of Mr. X's book and 8 B shaped just like the hill in our picture. move half -way down the hill. How shall MR.X. When near the top at "X", the plate cur- we do it? The method is to apply a rent will not increase very much no voltage or so called "bias" to the grid matter how much pressure we put on equal to the amount of "C" battery the grid. Besides this, the line is not shown in Fig. 2. This will move the straight, but it bends over sharply to the whole operation of the tube bodily from HD.z. right. This is like the roughness of the point "X" to point "Y". Fig. 1. Y's Children Have Advantage hilltop. There is one further advantage in this Best on Center of Curve case which is obtained. Up at the top to 67 or above, then this additional unit At point "Y" the line is straight and of the hill the height is great and this is well worth the bother and expense of slopes quite sharply. This shows that height represents the amount installing. of plate as the grid voltage is changed up and current. This plate current, it will be Living on a Hill down by the high frequency radio waves remembered, comes entirely from the "B" To illustrate the way this device works coming in through the tuner, then the battery, and if this is high it means a let us refer to Fig. 1, which represents plate current is varied in the same pro- great strain on the "B". By applying a hill with three houses on it. Mr. X portion, and it is this variation of the voltage "C" we have reduced the height lives at the top, Mr. Y. half way down, plate current which we hear through to about one-half. This cuts the plate and Mr. Z at the bottom. Each family the telephones. At point "Z" again we current down in the same proportion and has children who like to slide on their run into the two bad features-lack of doubles the life of our "B" battery. As sleds in winter time. Their mothers, straightness and also a. small change of a matter of fact, the more blocks of "13" . however, are a little bit timid about let- plate current (output) with the varying battery we use the greater will be the ting them go very far from home, but input. advantage of this shift. In a five tube allow them to slide only on the part of Take a look at Fig. 1 again. How can neutrodyne for instance, which uses 120 10 RADIO PROGRESS OCTOBER 1, 1924 volts, it is .sometimes possible to save nal carries the energy to the grid "G". netted to this amplifier with the result more than three-quarters of the "B" The other terminal connects through the that its output will work a loud speaker battery current by conecting in a "C" `C" battery to the filament. This al- with great volume. We do not recom- battery. 'ows the audio oscillation to vibrate back mend using a two step amplifier on a Three Advantages Of This Unit and forth between the grid and the fila- crystal however. The objection is that To review the reasons for the extra nent and so affect the input to the tube. all the amplifier can do is to repeat in a complication of a "C" battery, the fol- to far there has been no change since loud voice what was whispered in its lowing changes in the operation of the before installing the new unit. ear. Since the crystal detector is able to set will result as just explained. get music only from local stations, then 1. Distortion is reduced, which means Sliding Grid Down Hill the complete set will have no further that music and speeches will come When we consider the voltage on the range. If you are going to use two tubes through clearer than before. ;rid, however, we must notice that one' it will be considerably better not to use 2. Amplification is increased, with the side of the "C" battery, the negative, is the crystal detector at all but to em- onnected result that there is more volume of tone. directly to it, through the ploy the first tube as a regenerative de - 3. "B" battery current is reduced, ran.sformer winding. For this reason teeter and the second as an audio ampli- which prolongs the life of these expensive the grid has a negative voltage of 3, fier. units from two to five times. Jr whatever the value of "C" battery we At the left of the diagram you will see Ise. The effect is to slide it down the two How Connections Are Made leads labeled "from output of de- hill, as shown in Fig. 2 from the point tector." These run to the detector jack. If you are using more than 45 volts 'X" to "Y". It is now on the smooth If your set already has a jack then of of "B" battery and decide to improve teep part of the curve, and the benefits course, another one is not needed at this your set by inserting a "C" you will which we have already listed will im- position but if binding posts are used, prove the operation of the set. The then the two wires P to the binding post eason why it must be the negative pole represent these two that are shown. The OUT PUT )f the "C" which is connected to the jacks illustrated have only three springs. ;rid is this-notice that the tubes as If your are using four spring jacks then manufactured happen to have a loca - it is better to leave the third spring dis- ion at the top of the hill. Of course, connected and hook it up as shown. This his could not be predicted beforehand, was discussed at greater length in the "C" "A" ß but it is found to be true by experiment. article, "Judging Jacks for Real Re- since we Fig. 3. Connecting C Battery want to move down the hill we sults," in the September 1 issue of RADIO must apply a negative voltage. PROGRESS. If you prefer to use all four need to make only a few changes in the Some diagrams show the "C" battery springs it will not affect the hooking up hook-up. The theory of the connection onnected at point "W". As has been of the "C" battery in any way. is shown in Fig. 3. Here we have an explained in a previous issue of RADIO Two amplifier tube with the grid connected PROGRESS it is not such a good place to Tubes on One "C" Battery to the secondary of the audio transform- locate this unit. To be sure it puts a As you trace through the connections er as usual. The "A" battery is con- negative bias on the grid and for that you will find that the scheme is the same nected to the filament through the rheo- reason works just as well. But a'further as followed in Fig. 3. Only one "C" stat, which is in the negative side of action takes place. Since the "C" battery battery is needed, however, to operate the line, that is, it is the minus of the is now in the grid lead the latter can not two amplifier tubes. Indeed the same "A" battery which runs to the rheostat be as short as desirable, and besides this battery can be connected to any number and the plus goes of amplifiers, radio or audio. The direct to the tube. Be- `he zinc eases in which the cells of bat - grid fore the "C" unit is connected the dotted cry are packed will have a capacity ef- return from each of the tubes after pas- line represents the wire from the trans- "ect distorting the signals somewhat. sing through the secondary of its trans- former secondary to the "A" battery. In When it connected as shown in Fig. 3 former reaches the "C" minus binding order to insert the "C", it is necessary this capacity action to ground is missing, post. After going through the "C" to break only this one connection. Take since the "A" battery is already at battery it reaches the filaments by way out the wire between the transformer round potential. of the "A" battery. All the other units secondary and the "A" battery. In its of the set are standard in every way. place hook up the "C" with its minus to A Complete Hook-up The reason it can operate without be- the transformer and its plus to the If you understand the theory of the ing consumed is because it works like minus of the "A" battery. Of course, ?onnection shown in Fig. 3, you will 'be the expansion tank of a hot water heat- the dotted line will now be omitted, as Ale to follow the wiring diagram of ing system,. If you go down into your this wire has been removed. Fig. 4. Here is indicated the hook-up of basement and look at the hot water fur- Let us see what happens after making i complete two step amplifier, which may nace, you will notice a gauge on top the change. The output from the previ- be added to the detector of any set. That which will read 12 or 15 pounds, or per-

, ous tube (which may be the detector or is, a single circuit regenerative radio haps it may be calibrated to read the the first step) is impressed on the pri- uses the same kind of audio amplifiers height of the water in the pipes, which mary of the transformer.' It is stepped as does the most expensive super -hetero- will be 20 to 30 feet, depending on how up throirh the secondary and one termi- dyne. Even a crystal set can be con - tall a house you have. OCTOBER 1, 1924 RADIO PROGRESS 11

Where Does Pressure Come From? just as soon whether we use our set er the brick foundations to the new level This water pressure in your heating not. and from this time on they will support system is on all the time, winter or sum- No Circuit Through Battery the weight of the building. Again they mer, even after the fire goes out. How Referring once more to Fig. 3, observe have no output and are doing no work. is it" maintained? You will discover there is no complete circuit through the That is the difference between the this if you go up to the top floor of the "C" battery. The plus aide, to be eure, direct current "A" and "B" batteries building where you will see a large ex- is connected to the rest of the set, but on one hand which give out current and pansion tank. When first installing the the minus runs through the secondary do do the work and the "C" battery, which heater the plumber runs enough water the grid. There is no outlet from that supplies pressure but no energy. into the boiler and radiators so that the point. Of course, the high frequency al- water level rises up into the expansion ':ernating current operates the grid like RECEIVING A RADIO ROW tank. A glass at the side shows that the the trigger of a gun to control the out-, A fan in Rochester, N. Y., was listen water level is about one-third of the way put of the plate. Such high radio fre- ing to the play "A Night Off," which, up. When a fire is built in the furnace quency of about one million cycles per was coming in pretty loud from WGY. it heats the water and this causes it to second, or even the low audio frequencies The scene in which Mary Ann is ordered swell or expand slightly. The extra vol- of a few hundred will pase through the to her room began to come through. Tie ume is taken up in the tank, and so the capacity of the tube. Direct current on voices were so clear and could be heard water level rises to three-quarters full. he other hand will not run through the at such a distance that he had to tune When autumn comes each year it :s capacity of a condenser at all. It is the volume down almost to a whisper best to inspect the expansion tank and make sure the water 'level is about one - PI. E P P quarter or one-third of the way up. This often requires that a small amount of FRaq otpOr5AtKe JAc K Tack extra water be run into the system from OF OErecrwt Des. the city water main. This is called the 2nd STEP "make-up" water. It is needed to re- iOr.Y2 place the small amount which has been lost during the summer by leakage and by evaporation out of the overflow pipe which connects the expansion tank to the air. Notice that the pressure on the system is say fifteen pounds per square inch all o o (3 the time. It falls very slightly, of course, 45 V -i- if there is any leakage from the radia- L_ -1110-.,c>. - tors and when the makeup water is A cis» added it will rise again a fraction of a Fig. 4. A Il:rst-clasz T -:>o Stage Am 2lifier pound. But the point is that it does not l require a current of water to keep up blocked by the break in the circuit. Di- for fear 'the neighbors would think h:; the force on the boiler and radiators- rect current always must have a com- own family were having a row. that is maintained by the water at rest. plete. path in order to flow and when no path is provided no flow occurs. That is POLO PROVED POPULAR Station WJZ, New York, why the "C" battery has no output. transmitted It Uses No Current - the first direct -from -the -field descriptioh We all know that the life of the "A" As one further analogy of the action of a polo game on the occasion of the battery depends almost entirely on how we may compare the foundations of a opening match of the International Polo nmch we use our set. It may last a building. Suppose we have a two story Games, held at the Meadowbrook Club on week or a month, depending on whether house" resting on brick foundations. September 6th, and through the use of the we listen in until one o'clock, or are con- These bricks support twenty tons for a Western Union wire -link between the tent to say "good -night" at ten P. M. period of ten years and yet they have no WJZ studio and station WGY, Schenec- In the same way the "B" battery dies "output," that is, they do no real work. tady, the latter station simultaneously more from use than from old age, al- Now we decide to raise the house five broadcast the description. though the latter factor has some effect, feet and build higher foundations. We especially if we do not use the radio ;et a building mover to brine his crew EVERY ROOM CAN HEAR very much. In other words, we could of workmen and with pulleys and jacks A $2,000,000 apartment hotel-to be not use the set only one hour a week they raise the twenty tons to a distance the finest in the South-is to be erected and expect the "B" battery to last ten of five feet. They are doing real work at the corner of Church street and West years. It would have perished from old and they have an output which could be End avenue, Nashville, Tenn., in the near age long bëfore that dine But heYë ` s" `'treasured -in horse - power or in watts.: future, and every room in this building a surprising thing. The "C" battery When they get the building up to its will be equipped with a radio receiving gives out no current and so it will die -iew height, the stone masons build up ret. 12 RADIO PROGRESS OCTOBER 1, 1924

HEAR PRESIDENT COOLIDGE'S BAND WEAF's audience is occasionally privi- leged to hear a program by the United States Navy Band, played at the Sylvan Theatre under the direction of Charles Benter. This orchestra is composed of sixty-seven musicians and represents the United States Navy in Washington, D. C. It is detailed to play for the President whenever he cruises on the Mayflower, as well as on official occa- sions in public parks, government hos- pitals, and at the Capitol. This band was selected by the late President Harding to accompany him on the U. S. S. Henderson on his trip to Alaska. It was the only band in the funeral procession permitted to play. It is unique in that each of its members Roger Wolf's Cascade Dance Orchestra -11 can play both string and band instru- PICTURES OF POPULAR terest in Ido is increasing with the ments. PERFORMERS speed which follows genuine enthusiasm. Considering that this enthusiasm is We show here the photographs of two They Are Out of Stock likely throughout every civil- different orchestras, which are appar- to spread ized country of the world, it takes no A bulletin issued by Stern & Company, favorites, from the ently great judging wild flight of imagination to picture an Hartford, Conn., leads: comment which is received on applause international conference of the League To avoid confusion, the stock clerk cards. The first is the Cascade Dance of Nations being radiocast to every city, asks that we advise you we do not stock Orchestra, which broadcasts every Tues- village and home in the world in a man- and cannot furnish these articles: which made the day evening from the Biltmore Hotel. ner similar to that Oscillating Crystals. broadcasting of the American Republican Station \VJZ puts this on the air at 455 Regenerative Galena. and Democratic Conventions so spectacu- meters. The portrait of Mr. Roger Ohms in packages or bulk. lar a success in a language intelligible Wolf, who directs this group of players, in any dimensions. to all. Kilocycles appears in the medallion. of information for Ido in Umbrella antennas. A new addition to the list of famous The bureau is at l'Ido-Kon.oro, 83, Ground saturators. New Yo:k orchestras is Orlando': iio. e- France located Paris, IX. velt Hotel Concert Orchestra. They are rue Rochechouart, Amplication Constants. new to the New York public as they ap- peared for the first time on September 22 during the official opening of the new. hotel. These musicians were engaged by E. C. Fogg, managing director of the new hotel, after a careful selection of the leading classical organizations in the East.

IDO, THE RADIO LANGUAGE The Fourth International Idist Con- gress took place in Luxemburg from the 8th to 12th of August. The preceding international convention's occurred as follows: Vienna, 1921; Dessau, 1922, and Cassel, 1923. The representatives of 16 countries assembled in the historic capital of Luxemburg. All of the con- ferences and meetings employed only the International Language, Ido. In many European countries the in- O_iandJ's Orchestra OCTOBER 1, 1924 RADIO' PROGRESS 13 Radio On Army World Flight Troubles That Round -the - World Air Planes Met By LEE H. BAKER, Ensign, Radio Officer of the U. S. Coast Guard. TN an official announcement on the the work has been covered by other re- the Haida for suggestions. He evidently World Flight the war department stat- ports. It will be necessary, however, was pleased with our ideas as he em- ed the purpose of the expedition in these from time to time to give the positions bódied them in the plan. One of the few but sufficient. words, "To show the of the planes and to note their move- suggestions we made was to let the ease with which aerial communication ments in order that the radio work may Coast Guard operators do the entire may be established between the various be seen from a clearer viewpoint. work. The Air Service had secured per- continents and to obtain information Lieutenant Clayton Bissell, Advance mission for Naval Operators to be used about the operation of present type air- Officer for the first division of the flight, wherever needed. They were especially craft in various climates of the world." and Major W. E. Blair, weather observer to be used at the shore station. We be- An Army officer, in close contact with 'or the trip, were on board. These two lieved our operators could handle the the flight, has stated that one of the officers had frequent messages to send. work and secured permission to go ahead. greatest lessons of 'the trip has been The expected news of the flight in This permission placed the final word learned upon communication. If the progress kept the ship strictly on edge as on making the shore location a Coast Pacific is to be crossed as a regular ar as receiving was concerned. Guard station in every respect. A splen- business, then better communication must be established along the Aleutian Islands (off the west coast of Alaska) Between Dutch Harbor Naval Radio Station and Japan there is not a single radio station. Radio was imperative and vital to the success of the flight. There were three principal reasons: Why Radio Was Imperative First, the planes were hopping from three to seven hundred miles on each jump. It was necessary to know the weather conditions along the line of flight. These conditions had to be Fig. 1. Land Like This Surrounds Alaska Station known early in the morning so that the trip could start as soon as possible. Distant Landlocked Harbor did system of relaying reports was or- Second, if one plane fell during a hop, On several occasions we secured per- ganized and plans were perfected for a the others were to proceed 'to the near- mission from the Dutch Harbor Naval search in case one of the planes should est radio station and drop a note tel- Radio 'Station and opened up on the two go down. The whole thing was well done ling about the accident. This made it kilowatt ai c and sent press direct to and it would have been interesting to possible to send assistance within a very Estavan . Radio 'Station on Vancouver have seen it placed in operation. The short time. Island, British Columbia .(V A E) . In- complete plan was never used, as it was Third, publicity. The flight would be asmuch as the vessel was moored in a not needed. of little value if the people of the United landlocked harbor the results at sixteen States were not informed of its progresa. hundred miles were pleasing. Major Martin's Plane Falls This news was wanted at once by all the The section through the Aleutians rep- An accident to Major Martin's plane various news organizations of the coun- resented the hardest part of the World upset our calculations. With the assist- try. Radio was the means of getting Flight. Figure 1 shows the character ance of.the Algonquin he had succeeded the news out. of much of the ground covered. Dis- in reaching Chignik. The only report These three reasons caused the radio tances were carefully calculated. The received was from Chignik, telling that work in connection with the World Flight cruising radius of the planes and assist- he had left. Far hours the Haida and to assume extraordinary proportions. ing vessels was considered. The radio Dutch Harbor listened in for news. The Most of the radio work through the Ale- equipment of the vessels was considered. other points had not seen the plane. This utian Islands was done by the Coast Definite stations were assigned for each meant that he had not passed the first Guard Cutter Haida. hop. The details were largely worked reporting station, King Cove. The plane This article will not attempt to outline out by the Advance Officer, who sub- must have fallen between Chignik and the . progress of the flight. That side of mitted them to the Radio Department of King Cove. 14 RADIO PROGRESS OCTOBER 1, 1924

The Algonquin was in that vicinity of Education. The set was more or less This system of reception had been and at once started a search calling for of a wreck. The Edison batteries had tried before on this vessel and it had assistance from the cannery vessels near- been exposed and almost ruined. The been found that we could read signals by. The Haida, carrying the Advançe power plant was a. hopeless wreck, due with the tube in the regenerative stage Officer, left to assist in the search. to the fact that some enterprising na- which we could not detect with the tube For three days the heaviest radio traf- tive had used it as a chicken coop. Water in ordinary oscillation. This is not fic poured in and out of the Haida,-false had leaked in and damaged the receiver. given as a hint to other operators be- reports and reports containing no news, The antenna was being used by the cause we do not ordinarily use it here. directions, orders, and suggestions for a Aleuts as a rack for drying fish and as The whistling noise does anything but better search. And through the whole a clothesline. soothe nerves. When you have received work the inevitable press dispatches had The Haida charged and cleaned the long weather reports with the tube to be sent out nightly to Estavan. The batteries, sent a spark coil ashore for whistling six or seven times a day, and world was interested and dependent on use as a transmitter, fixed up the re- you have a group of flyers lined up be- Coast Guard Cutters for news. The ceiver, cleared fish and clothes off the hind you all the time, you forget nerves. Haida on this press work used the half antenna, installed new insulation, and Six Nations Sent Signals kilowatt spark set and successfully in other words placed the station in worked Estavan at a distance of fifteen operation. For an operator we Used The weather information from the hundred miles. It was not until the one of the school teachers who knew Eider was the most important radio work fourth day that Major Martin was lo- Morse Continental code and all mes- the Haida carried on in that it had cated and rescued. sages between the Haida and the shore to do directly with the progress of the flight. Due to the difficulties of com- Describing station were sent in that code. the Apparatus munication with the Eider and the pos- In order to understand this work it is Six Wire Squirrel Cage sible chance of the flyers being without necessary to outline the radio equip- The transmitting set was built by the reliable weather information, the Haida ment of the participants. The radio Haida on the way north. It consisted of established' a supplementary weather equipment of the Haida is same the as four five -watt tubes in pai?allel. For service. This was accomplished by get- when she was originally commissioned. ting in communication - an antenna we constructed a squirrel with all trans The main transmitting set consists of Pacific ships on the age, six wires about sixty feet long. great circle route. a two kilowatt are. The arc has proved This route comes north and nearly We figured in case of necessity that extremely satisfactory on high wave touches the Aleutians. We were receiv- we had enough battery power to main- lengths. When used on low wave ing hourly weather reports from six ves- tain the station continuously for forty- lengths results have not been note- sels of varying nationalities. The co- worthy. This type of set for a cruising eight hours. We used thirty-six hours operation and interest of these foreign cutter on Coast Guard duty is not desir- as the safety margin. We found that vessels made this factor of the work very able, in as much as most of the messages with the available power we secured best agreeable. The vessels did all possible sent are of few words. For the flight results using two tubes, rather than to assist the Haida in working the Eider work, especially press, the set came four. We also had an auxiliary trans- but were not of material assistance as through splendidly. mitter consisting of a spark coil oper- relay vessels. The auxiliary transmitting set is a half ated by dry cells. '7e11 Pleased With Work kilowatt spark. We secure ten amperes 100 San radiation on this set. The spark has Stretching Ears Miles Francisco is twenty-six hundred been used as the main transmitting set By the time the Haida reached Atka miles from Atka. The Haida maintained practically ever since the vessel has the Eider, another Coast Guard vessel, a daily schedule with San Francisco been in commission due to difficulties was five hundred miles distant. The (KFS) . The average press message con- with the arc on the lower wave lengths. weather reports from Major Blair had tained two hundred words. The Haida The antenna of the Haida is largely been received and it was quite some received an acknowledgment immedi- responsible for the results on the flight work. The first day brought our oper- ately on every message. In no case was work. This aerial is as originally in- ators nearly to the fighting point con- it necessary to repeat any part of a mes- stalled. Insulation has been carefully cerning the Eider. She was sending to sage. San Francisco reported strong re- watched. The trouble usually arises her full capacity, four hundred miles, ception. The Associated Press sent the from leakage at the lead-in insulator and we were stretching our ears and re- Haida a radiogram of congratulation on when the arc is in use, but this trouble ceiving the other hundred of the dis- the speed, dispatch, and accuracy with has been eliminated by. giving the in- tance. The Eider's signals were so weak which this press work was handled. sulator an occasional paraffine bath. that at times it was necessary to stop The information contained in this re- every motor on the Haida in order to port will undoubedly be instructive to Chicken Coop and Clothesline eliminate all possible ship noises. The all who are interested in the Air Ser- Another set in use to the westward signals of the Eider were then heard by vice. It explains the great need and was the shore station at Atka. When moving the tickler coil to nearly the vital importance of radio communication the Haida reached Atka we found an limit and causing the tube to whistle in connection with any project which old radio set which the Algonquin in- continuously. The tube thus acted as au has to do with the establishment of regu- stalled some years ago for the Bureau oscillator. lar air routes for inter -continental travel. OCTOBER 1, 1924 RADIO PROGRESS 15 Feeding Music to the Air Inside a Sending Station With Up-to-date Equipment By ALFRED N. GOLDSMITH, B. S., Ph.D., Fellow, I. R. E.; D;_rzctor of Research, Radio Corporation of America T seems to many broadcast listeners radiotrons or vacuum tubes which are 'hey are not designed right, an annoy- that their nightly concert arrives necessary for sending. ing hum will be heard all the time in like rain from heaven, and there is little These radiotrons also require voltage the receiving set. inquiry into its source. ' The actual for both grid bias and plate, just like the There are generally four large radio- origin of the evening's entertainment is, vacuum tubes in your receiving set. The trons in the transmitter in the Class B however, in a most interesting electrical grid bias voltage is readily obtained from 500 -watt stations. Two of these vacuum masterpiece, namely, the broadcast trans- dry cells or from a small generator, being tubes are called oscillators, and the other mitter. may It truly be said that a more about forty or sixty volts. The plate two are termed modulators. The oscil- carefully designed and better working pressure is much higher, and it is nece,. lators produce a continual series of elec- piece of equipment than the sending sary to supply several kilowatts of power trical vibrations of very high frequency transmitter can hardly be found. The at two thousand volts for the largest actual wiring and circuits of the trans- radiotrons in the stations. A large mitter are somewhat complicated, but motor of several horse power drives a the main parts and their various func- powerful generator which furnishes the tions are easily understood and worth necessary 2000 -volt supply. Such high looking into. volta-ges are dangerous to life, and the Fig. 2. Af er Wave is Modulated A broadcast station must send circuits have to be carefully guarded out a continuous stream of radio waves against accidental contact. That is why and considerable power. They are, in of proper frequency, and these must be the transmitters are generally enclosed fact, devices for converting the high vol- controlled in such a way that they carry to a large extent by panels and grills. tage direct current which is supplied to the speech or music accurately to your them into an alternating or vibrating radio set, and with enough power to give Filtering Out the Hums In order that the current furnished to current of very high frequency (about good signals at reasonable distances. 1,000,000 the transmitter radiotrons shall be per- cycles per second) , and the ease, regularity, Changing the City Power fectly steady and free from any varia- and smoothness with which they accomplish this is very re- Of course there must be an electrical tions or ripple which would cause un- markable. The output of án oscillator power supply for the sending station, pleasant sounds in the receiving set, tube has a wave which is shown and this is usually obtained from the special circuits called "electrical filters" in Fig. 1. Both loud and soft waves local are arranged through which the currents power company. But the custom- are indicated. ary 110 volts of the city electric com- pany is not suitable for most of the What the Modulator Tubes Do electrical equipment of the transmitter, The modulator radiotrons have a dif- and so more apparatus must be used to ferent purpose. They control the alter- produce electricity at the right voltages, nating current produced by the oscilla- or electrical pressures, to operate the LOUo WAVE tors in such a way that the speech or various radiotrons . in the transmitter. music being sent from the station is im- Accordingly, there is frequently a sto- pressed on the output of the oscillators. rage battery charger, consisting of a I -TIME See Fig. 2 for the effect of modulation motor which drives a generator, the on the wave shown in Fig. 1. This car- generator in turn charging the storage rier wave oscillates 1,000,000 times per batteries which are required for the sta- SO FT WAVE' second, the modulated wave 500 times. tion. The battery charger unit is much Fig. 1. Waves from Oscillator It is as if the oscillators produced a like the small lighting plants now so steady stream of energy, and the modu- widely used on the farm, except that it pass to be smoothed out before they get lators controlled this flow in accordance is driven by an electric motor instead to the transmitter. These are described with the sound waves originating in the of a gasoline engine. Suitable storage. in another article in this magazine. They broadcast station studio. Or to put it batteries, usually supplying pressures are expensive devices, but on their effi- in another way, in the form of a rough around ten -or twenty volts, are generally ciency depends the quietness of the radio analogy, the oscillators produce a flow used to light the filaments of the large when no music is being sent out. If of energy which the modulators control 16 RADIO PROGRESS OCTOBER 1, 1924

and work into a signature of the music going out of the station. The oscillators- act like an electrical pump, producing smooth and steady pressure, which produces no sound in the receiving set. The modulators are a sort of controlling hand at the throttle of the valve through which the oscillator power flows, and they impress on this flow the music which is heard by the listener. Either set of tubes alone would be useless; it is only in combination that they can produce the controlled electric waves which carry the entertainment. Stations Look Complicated Of course this production of alternat- ing currents by the oscillator radiotrons and the control of such currents by the modulators require a great deal of elec- trical apparatus to be connected to these tubes, and accordingly the rear of a broadcast station transmitter is a com- plicated mass of electrical devices, all of which have to be thoroughly tested to Fig. 3. Transmitter with "Tank" Circuit ensure reliable operation of the station. are connected In the case of the transmitter. shown in to the combination of os- of light. This flickering line is observed ..illator the accompanying photograph, Fig. 3, and modulator tubes and are fed by the engineer to make sure that the which is the type used in stations WJY, by them. That is, the oscillators and control is both sufficient and accurate. modulators WJZ, and, WRC of the Radio Corpora- together supply the electrical This modern method of watching the power tion of America at New York and Wash- to the antenna and ground, from quality of the broadcasting is very help- a hick ington, "tank circuits," so-called, or fil- this power is then sent out as ful in obtaining high-class reception. Be- ters, are provided to make sure that the radio waves, which travel outward in all sides this, the control room engineers directions. waves sent out by the station are en- listen to the performance on a radio tirely of one frequency so that they will Taking a Radio Sample while they are sending, so that the sta- not cause interference at other frequen- While the power is being sent out, a tion is checked by both eye and ear, and cies, and thus disturb other communica- small sample of it is taken in the send- so is kept up to standard. tions. ing station and sent to the control room, In the stations just mentioned, in order to make sure that the programs TRANSMITTER-. are not interrupted, all the transmitting equipment which has been described is CONTROL CONTROL provided in duplicate. Then ROOM there are OSCILLOGRAPH. ROOM AMPLIFIER RECEIVER. electrical relays, by which one transmit- BATTERY STORAGE ter or the other can be instantly thrown CHARGER BATTERIES POWER SMALL "on the in case of need. requires ANTENNA air" It AMPLIFIER only the touch of a button to switch RADIO from a disabled transmitter to the spare NAVE S CITY MOTOR MODULATOR one, which is always ready POWER to take up GENERATOR RADIOTRUNS SUPPLY FOR FILAMENTS the work. This is another great step

ANTENNA toward turning broadcasting into a pub- lic service of the most reliable sort. Fig. 4 is a drawing which shows how the MOTOR OSCIL ATOR GENERATOR FILTER 1- RADIOTRONS GROUND parts are related. L FOR 2000 VOLTS When you remember that spare radio- F ig. 4. Diagram of Relations Between Parts trons, batteries, meters, etc., must be supplied for an up-to-date transmitting The actual radiation or "throwing - where it is run through an oscillograph. station, it will be seen that the radio off" of the radio waves is accomplished This piece of apparatus shows the con- concert is the result of great expense and by an aerial wire system, that is, the trol of the outgoing waves by the music constant care, and that broadcasting antenna, and a ground connection. They in the form of a complicated waving line mission is not to be undertaken lightly. OCTOBER 1, 1924 RADIO PROGRESS 17 Cutting Down the Losses How to Make Your Receiver Follow Trend to Low Loss Receivers

By C. WILLIAM RADOS

THIS article is intended to help the wet. A good ground is quite satisfac- neighbor's set. All coils to be most effi- reader improve his radio set or to tory, but a two or four -wire counterpoise cient should be wound on forms having build a new one correctly. It does not is often better. All back yards are dif- as little solid dielectric (insulation) as describe, nor is limited to, any one re- ferent, and fortunately the shape does possible. A thin cardboard tube is good. ceiver. These remarks apply to any and not matter much, but all wires must be Basket weave coils (such as Amrad) are all receivers, from a 98 -cent crystal set of equal length and also well insulated. very good as they contain very little to a 10 -tube super -het. As all these It is good practice to bring each wire dielectric. The ideal coil would be wound points are of about equal importance, up to the receiving set. The height above we shall start at the antenna and fol- ground is not important, from 1 to 10 low through to the phones as logically feet being satisfactory. as possible. Primary Sharp Antenna Circuit The antenna condenser, if used, need Beginning with the antenna, therefore, not be larger than .00025 mfd. (micro - we want this circuit to tune sharply for farads); that is, 11 plates, as very few two reasons. One is outs out that it antennas require more than this capac- more interference, and the other is that ity. In fact, if the primary or antenna when low we couple a resistance circuit coil has several taps, a condenser half to it, the latter will not suffer loss in this size (five plates) will do. The ad- loudness, caused by trouble in the aerial. vantage in using a small condenser here To have resistance a low antenna, one is twofold. First, we spread the tuning should use of wire a continuous stretch out over the whole condenser scale, and 17i,-. 2. How to Place Tickler from free or end to lightning arrester second we may get greater signal on air, but practically the wire has to set, and it should be well insulated. More strength. Vacuum tubes are voltage have some support. A sketch of a low than one wire is unnecessary, as a one - operated devices, which means that the loss form is shown in Fig. 1. Use no wire antenna will get practically every- more .the input voltage, the greater the more will. Of course, varnish or other "dope" as they increase thing that two or output voltage. The larger the coil we the losses of the circuit. Bore small if the length of the aerial is quite short, have in circuit the greater the antenna owing to the your back yard holes in the ends, and pass the ends of fact that voltage across it, and so we get louder is an ad- the wires through, making them secure small, then there is sometimes volume of music and voice. Large sizes vantage in using two wires, if they can in that manner. be spaced fairly far apart. For instance, Well built low loss condensers are if the greatest length of wire you can available now and are absolutely neces- get is, say 40 feet, then additional vol- sary. For examples of real low loss con- ume can be got in your set if you will densers, see the new Acme, Premier, and use two 40 -foot wires, spaced at least General Radio condensers. There are four or five feet apart. If they were many others, also. Among other things strung only a foot apart, the added necessary, the connection to the rotor amount of energy received would be should be through a pig tail instead of Fig. 1. Low Loss Winding negligible. Each wire may be thought a friction contact, or else a stiff spring; of as receiving practically all the radio of wire, up to No. 14 doe (double cotton the insulation should 'be hard rubber or waves within a distance of several feet, covered) can be used here. genuine bakelite, and the vernier should and that is why when they are too close be a mechanical affair instead of a small together they do not help each other. Secondary separate vernier condenser. Separate Porcelain, quartz, or glass insulators If we are using a double circuit tuner vernier condensers introduce additional are among the best. Composition insu- (separate coils for primary and second- losses, so it is much better to use a me- lation is always to be suspected because ary) the secondary should be wound on chanical vernier, friction or gear drive, it may absorb water. If possible, do not the same form or tube as the primary, or the style with an extra plate on the string aerial over trees or bushes, etc., but an inch away. This will help re- main condenser. For cutting down the an they cause losses, particularly when duce radiation, which squeals in your bad body capacity effect, the secondary 18 RADIO PROGRESS OCTOBER 1, 1924

condenser must be connected with its the set. When -199 using UV or WD -11 is set at the filament end of the coil so rotary plates hooked up to filament, tubes, use the proper sockets; adaptors, as to keep it as far as possible from the which is grounded. especially with the UV -199 tubes, rob grid. By this location the effect of the When a condenser is used in the aerial, the tubes of much of their radio fre- tickler on the grid in the way of chang- as in a single circuit tuner, then the quency advantages. Fibre panels are to ing the wave length is greatly reduced. rotor, plates go to the aerial and the be avoided because they may absorb stator to the grid. This is in tine with moisture. Cabinets should not be too Advantage of Split Secondary the universal rule that the stator always small. The sides and cover should be Fig. 3 shows a "split secondary," goes to the grid. The reason for this at least an inch away from the parts which allows movement of the tickler inside, if possible. without affecting the tuning or wave length. The grid coil should be about Plate Circuit Adjustment 15 turns on a 3 -inch tube and the tickler Tickler regeneration is better than about 27. The grid coil should be at variouieter tuning because the movement least five inches from the secondary coil. of the tickler does not affect the wave Fig. 4' shows how this arrangement is length of the set so much. The tickler mounted up. Fig. 5 shows a fixed tickler

Fig. 3. Split Secondary Coils

was explained in the September 15 issue of RADIO PROGRESS. The Grid Leak and Condenser Needless to say, for good results we must have a good grid leak and con- denser. Pick out the sizes recommended for your particular tube and use well - made apparatus. Cartridge and graphite leaks are good. Keep the lead to the grid up in the air away from everything, Fig. 4. Mounting and Hook-up of Split Seconda,ry and as short as you can. Also mount for minimum shift of wave length should which is easier to mount up and make. the grid leak and condenser on bus bar be about half the diameter of the coil This also varies the regeneration with- so they will not touch against panel or inside of which it is placed, and should out varying the secondary tuning. Con- cabinet. The socket is best made of hard have as few turns as possible. The way denser Ct brings the tube in and out of rubber, porcelain, or bakelite. Sockets to find out how many turns to have is oscillation very easily. The way the set operates is this: The secondary, which is tuned by condenser Cs, feeds its energy through the grid condenser to the grid of the tube. The output energy from the plate goes j / / through the tickler coil and over to point / / X, where it divides. The low, or audio P/ /S iT frequency, cannot pass through the small i capacity of Ct, which will consist of 11 - / / , plates. It can, however, flow through the telephones, where it is converted into music in the diaphragm. The radio fre- quency, on the other hand, which also has come from the plate through the I ig. 5. Fixed Tickler Coil for Regeneration tickler coil, is unable to flow through the heavy inductance of the phones. High with metal shells are not quite so good to pull off turns one by one, until, at frequency will pass a small condenser, as they introduce some extra capacity. the highest wave length to which the set however, and so its path is from X If a cheap "molded mud" socket is used, willrespond, the tube will just oscillate through Ct, back to the filament. The it probably provides you with another when the tickler is at maximum. See grid leak and so spoils the operation of Fig. 2 for proper placing of tickler. It Continued on Page 24 OCTOBER 1, 1924 RADIO PROGRESS 19 High Powered Station Will Open Soon WLW Cincinnati Will Soon Have a First -Class Transmitter in Action

THE new five -kilowatt transmitting steel. The aerial and lead-in are of the is on the outside the current flows station, WLW, of The Crosley Radio type known as the squirrel cage. They through practically the entire volume of Corporation, Cincinnati, Ohio, will be consist of a dozen wires strung evenly the metal, and this reduces the resist- placed in operation about Christmas around the edge of an insulating disk. ance to a very low value. The lead-in, time. This new super -power station will The advantage of this type of construc- of course, is in the circuit and so it is be the latest radio achieve.ment of The tion is this. As is well known, high fre- constructed in the same manner. Western Electric Company, containing quency waves of several hundred thous- The aerial is of the, well-known T all of the improvements known to the and vibrations per second have a very shape. This gives a transmitting effi- radio engineers. pronounced tendency to crowd to the out- ciency practically the same in all direc- Radio's progress is marvelously rapid. side of a wire. Over 99% of the current tions. For a station located near the Beginning with the .five -watt transmit- flows in a thin skin only a few hun- center of the present interest in radio, ting equipment of only a few years ago, dredths of an inch thick and the entire this is a good feature. The lead-in is the power of the transmitter gradually central part of the wire carries no cur - tied to all of the wires in the aerial at has increased until it is now necessary to remove the sending station outside of the city limits in order that no in- terference will occur when WLW is "on the air." Located on Highest Point After a careful survey of the counties surrounding the WLW- studio, a point outside of Cincinnati was selected by the radio engineers for the erection of two 200 -foot antenna towers, and the broad- casting station. The design will be unique and contain not only the power- ful broadcasting equipment, but in an adjoining building the resident opera- tors will live. From the top of rtlre towers. located on a knoll at the highest point for miles around, a marvelous view of the surrounding country and three states may be had. Heavy wires lead from the antenna through the dome of the station, the roof of which has been designed after a famous observatory. The tall towers piercing the sky will be an inspiring sight above the white, massive station and house. Heavy stone walls surround Fig. 1. Notice Special Aerial and Le id In the buildings, but the large gate will always be open to visitors. Landscape rent at all. Of course, this increases the the center point, although this does not gardeners already are busy with their resistance considerably and cuts down show very clearly in the picture. the amount of the current, and so re- plans for beautifying the grounds, and Just Push the Button gravel walks will be lined with shade duces the loudness of the program trans- Operation of this new station will be trees and gorgeous flowers. mitted. By using the squirrel cage con- struction, the copper is distributed all automatic. Within five seconds after a Why the Squirrel Cage on the outside of a good sized circle. button has been pressed in the broadcast- ing studio, located in the administration In the photograph you will notice that The center part of the squirrel cage is the towers are graceful structures of entirely missing. Since all the copper Continued on Page 20 20 RADIO PROGRESS OCTOBER 1, 1924 Third Radio Conference Coming This Will Have Big Effect on Interference

sECRE'I \RY HOOVER of the Bureau casting stations. Limitation of power; miles away from of Commerce has just called a national division the station. Special of time; zoning of broadcasting wires will conference for the voluntary regulation be used to carry the music of stations. Means for distinguishing the from the radio. The date originally announced artists and studio director to identity of amateur calls from foreign the was September transmitting station. By means of 30, but this has been countries. Interference by electrical de- line -amplifiers, which are like your changed to October 6. Two conferences vices other than radio transmitting audio sta- steps, the music is kept at the same qual- like this have already been held, one in tions. Relations between Government ity that would be found if February, 1922, and the other in March, and the broadcast- commercial services. Such other ing were done 1923. Both of these were well attended in the same room with topics as may be proposed by the confers the artists. by the representatives of the various or- ence. ganizations who were interested. You To help the work of the conference a Monk's Cloth Hangings will remember that when Congress ad- representative will be asked from each A research into the accoustical quali- journed last June, the Control Bill, of the various groups who are interested ties of the different broadcasting studios which was before the House, was lost in in radio. These representatives will resulted in planning of the new WLW the rush of unfinished business. meet to form an Advisory Council. One parlors along the best lines. At the The result of the two previous meet- representative is now being invited from recommendation of Dr. D. C. Miller, ings has been a decrease in the misun- each of the following: Listeners, marine heavy monk's cloth will be used to drape derstanding and trouble through the vol- service, broadcasting (one from each in- the walls, while the ceilings will have untary co-operation of the broadcasting spection district) ; engineering, trans- a special membrane treatment. Noise- stations, the manufacturer and the pub- oceanic communication, wire intercon- less ventilators keep the temperature of lic. Because of this, interference has nections, manufacturers, amateurs, point- the studios at the proper degree, regard- been reduced and the service generally to-point communication, and the Govern- less of the atmospheric conditions. The improved. Secretary Hoover states that ment departments. The committee so polished hardwood floors will be covered experience has well demonstrated that formed will hold public hearings. All with heavy rugs to prevent unnecessary even the most expensive and elaborate persons or organizations having any sug- noise. receiving sets cannot be depended upon gestions to make or views to express Plate glass will permit a view of to get the distant stations with very upon any features of radio activity are the artists in both studios from the au- great regularity. The future of radio, urged to attend and will have full op- ditorium where the guests will find com- he thinks, lies in developing local sta- portunity to be heard. fortable seats. A triangular -shaped am- tions or those within a few hundred Some of the matters suggested for con- plifying control room is located between miles, rather than the fad of trying to sideration are not within the regulatory the solo and group parlors, where the pick up 1500 to 3000 mile distances. If control of the Secretary. As to such studio director and his assistants will this trend is kept Up, then interconnec- matters, any conclusions reached by the work. Several improvements will be, tion will be a very important factor in conference can become effective only by found for the convenience of the artists the future. voluntary adoption by the interests af- which will make the waits between pro- fected. As to the features falling within gram numbers but five seconds. Radio Service Bulletin the powers of the Secretary the recom- The growth of radio, and particularly mendations of the conference will be ad- the multiplication of broadcasting sta- visory to the department. DON'T DISTURB THE CHOIR tions and the consequent congestion of The appreciation of the aged for radio the air, has made necessary a considera- broadcasting is illustrated by the letter tion of many subjects and perhaps a re- HIGH POWERED STATION of Mrs. Helen M. Laird of Mohawk, N. vision of some present methods. Some Continued from Page 19 Y., to WGY, Schenectady, recently. Mrs. of the matters which will. be discussed building in Cincinnati, the voice of the Laird is eighty years old and for two and considered at the conference are: artist wilt be sent into the ether and years she has been a shut-in. Referring Revision of the present frequency or perhaps heard in Cape Town,- South to a broadcast church service, she said; wave length allocations to reduce inter- Africa, as was a similar station equipped "I could not refrain from joining last ference. Use of high frequencies or short for experiment. night in the singing of the good old waves. Classifications of broadcasting Remote control will be used, making hymn, 'Come let us join our cheerful stations; possible discontinuance of class it possible to have the microphones in songs,' and if I made discord to disturb C stations. Interconnection of broad- either the studio, theatres or other places the choir, I must apologize." 21 OCTOBER 1, 1924 RADIO . PROGRESS Broadcasting. Over Phantom Line How This Is Done by a Big Chicago Station

By WALTER G. EVANS, Announcer of KYW, Chicago

IT is well known by this time that An outside or "pick-up" operator is broadcasting music or speeches over the many events which are broadcast do stationed at the end of each line over same line without interference between not occur in the studio at the sending sta- which a program is to be transmitted. the two. Not a trace of cross talk can tion, but take place in their natural For him radio holds no thrill, no mys- be distinguished between these two chan- haunt. For instance, it would not be ..ery. He passed through that stage long nels over the same line. In the parlance very practical to transport a church into ago aboard some ship watching the sun of the telephone companies this trick is the studio in order that the Sunday ser- come out of the ocean in the days when known as the simplex to ground or phan- vices could go on the air. radio was called wireless. :om circuit and in the broadcast field his watch to KYW has been the first to take advan- Since the place where the program oc- The pick-up man checks in the sta- tage of this method. curs is some distance, perhaps several the second with the operator for his pro- Fig. 1 is a diagram showing how con- miles from the sending aerial, it is of tion, and as time approaches he his amplifiers nections are made for this particular cir- course necessary to connect these two gram to begin adjusts notifies the an- cuit. Telephone A is an ordinary instru- spots with a telephone line. This line and microphones and nouncer by. When the program ment and talks along the line to.a sub- should be particularly good because any to stand scriber at the ether end, whom we will noise or humming would go out through is ended at some other place, the sta- call A'. B is a similar instrument. the air to the whole surrounding coun- tion operator pulls the plug and inserts Either one of these phones may be the try. The natural thing to do would be it in the next line, and tells the new the cirouit. The out- one which you use in your own house. to pick out a partioularly good pair of operator he has to The phantom line is connected in through telephone wires and use them for trans side operator tells his announcer the "repeat coils" as shown. These are mating the music to the studio. As a '`shoot" and the switch -over has been completed. no hing more than induction coils, with matter of fact, however, the sen a tap or connection taken at the middle company does not use an ordinary tele- Seconds Are Minutes When point of the windings. The two taps phone line at all, but rather a "phantom Every effort has been made to reduce 'form the connections for the two lines line," which does not really exist, to the time element in switching from point running to phantom P. At the other send a great deal of their performances. to point for at the receiving end a silence end of the wires there are two more P Just how this is done and how the of ten seconds will seem like as many coils connected in exactly the same way switching from one line to another is minutes. For this reason all schedules and another telephone P". (,uried out, will be explained. must be run on a split second basis and everything must be in hair trigger readi- Louder Tone with No Wires Out of Thirty Picking One ness: It will seem a surprising thing, but For instance, you will hear the an- Six men are employed at KYW to the phantom line which uses no in'livi- nouncer, say, "And now we'll switch you maintain and operate the outside pick- dual wires gives clearer and louder back to the Congress Hotel for a half ups. All of the equipment is inspected speech than the regular circuits do. The hour's dinner music." Have you ever daily, batteries kept in top notch condi- reason is because instead of having a wondered just what takes place during tion and lines tested for noise or cross single wire to carry the current each the two or three second interval while talk. Microphones may, in the language way, it employs two. The direction of the program is shifted from one location of the operators, "go south" over night the current is shown by the arrows. Of disappointing- to another? It is almost due to temperature changes, moisture, or course the direction changes several hun- ly simple. The thirty -odd lines from the mechanical jar. At practically every dred times every second in all the lines, different points from which KYW broad - point duplicate equipment and batteries (lists end in a telephone switchboard not the exact speed of oscillation depending insure against unlike the one you see every day in your are installed to interrup- on the pitch of the note which is being onler office. Both broadcast and talking tion.of your program. sounded. For instance, Middle C has a circuits by come through this board, and The Phantom Line period of 256 vibrations per second. The means of plugs and cords any line or of the trade in use arrows show the current direction any comhinnlion may be conducted to the One of the tricks broadcasting set, or to the station oper- at KYW permits us to talk to the out- one instant. A small fraction later of ator's telephone. side operator over one line while we are course, they will all have reversed. The 22 RADIO PROGRESS OCTOBER 1, 1924

arrows shown in heavy line give the in- no cross talk at all is heard with such a THE LADIES FROM HELL formation in regard to the main lines, combination. To receive a letter from one of the A and B. It so happens at the instant In the picture the phantom phone is "Ladies from Hell" would considered the current is flowing out shown as being used for broadcasting. startle any calm -minded individual. through the upper line and in through This, as has just been explained, is be- To learn that the lower one. This direction also holds cause it will give the clearest and best a radio program had been enjoyed by this for telephone B. reception of the three. The other two "lady" in 'her super -heated environment, The direction of current flow into can be used for any purpose at all. The might show a remarkable feat of broad- phanton is illustrated by arrows drawn op one is here described ad being re- casting. dotted. Assuming that it is down at the served for the director to use in giving The man who reads the thousands of left and up at the right, then the cur- his introductions. If the event, which letters received by rent in each case divides at the repeat is being sent out is a particularly im- WGY, Schenectady, noted that the "lady" coil. One half will go up and the other portant one, like a message from the gave "her" ad- dress as "Care Groton half down. It is necessary in building President of the United States, then it Country Club," of Groton, Mass., and he recalled that dur- ing the war one of the most famous QRoAD CA 87 fighting units in the allied forces re- ,. Music HERE ceived the blunt, yet complimentary, de- 1 signation of "The Ladies from Hell." The letter verified his conclusion that piRf cTOR S it was from a former soldier, who had bN57/juGTlo/1/s listened to the New York Philharmonic orchestra and also a radio drama. "Please extend to them the thanks of our small family," he added. "These con- %a PH uNE certs mean a lot to ex -service men trying to regain their health." C PvßcirTA[.kf¢ERF_

STRINGS PROBABLY ARE BEST 7o PHO/Vc 3 __-._ There is considerable debate among radio listeners as to which instrument Fig. 1. How a Phantom is Connected transmits by radio with the greatest 'fidelity but, so far as a group of instru- these coils to balance them, that is, make is quite likely that line B will be held ments is concerned, string instruments them equal with the precision, greatest as a spare, and in that case if either A leserve the laurels. so that exactly half the current goes or P should fail, then B could be pressed each way. When this condition is into the service to take its place. obtained then the current from P has no UNIVERSITY affect at all on either phone A or B be- Putting on the Soft Pedal WILL BROADCAST cause it is exactly balanced. It is just Another development which was origi- COURSES as if two friends tried to make you move. nated at KYW permits the music at out- With the opening of the University of If one pulled North with exactly ten side pick-ups to be actually tuned to bal- Pittsburgh in the fall, radio fans will pounds, and the other South the same at ance at the station. If for example, the be entertained from time to time by the instant, with precisely the same pull of high notes from broadcasting of various courses ten pounds, then while it might hurt a dance orchestra are of in- your arms you would not move in either predominating the operator merely ad- struction by KDKA from the education- direction. justs a rotary switch until the lower al studio which was established last toned instruments come through with March at the University of Pittsburgh. Current Not at All Confused sufficient volume to give the desired Two educational series were sent out dur- When a current reaches the other end quality. If low notes are too loud it ing the spring term. A course on Political of the line you might think that it would get mixed up, since there are only two can be similarly adjusted to increase the Parties was broadcast due to the great pairs of wires for three instruments. volume of high notes until they balance. 'nterest in politics as shown in the re- However, the electricity is not a bit con- In picking up programs from more cent national party conventions, and fused. Current that circulates in one distant points such as the recent Radio whenever possible similar courses about line and out the other affects phone A'. Show at Milwaukee, or the football national affairs will be put on the air. The same is true of phone B' in its line. games at Urbana the procedure' is about Outlines for each of the And current which goes to the right in ;he same, although repeaters, or boosters courses to be both lines of A and to the left in both are sometimes inserted in the line to keep broadcast will be printed and distributed lines of B affects phone P. In this way the volume up to standard. - to those who are interested. THAT MESSAGE FROM MARS he signals when they arrive. ings in the evening. THE papers have been full re- 1`he messages were supposed to There are various modifications cently of mysterious messages. :onsist of dots and dashes. Sup- 9f them, but we will describe the These are supposed to have been 9ose you go down to a telegraph form that seems easiest. In the sent out from the planet Mars, station and listen to the ticker first one the knowledge of outside which is now at the nearest point ;rinding out click -click, click, stations and the announcers' of its approach to the earth. The low long do you suppose it would voices is very important. The peculiar thing about the messages take you to guess what they were company assembles in a large is the very long wave length, ;aging if you don't know code? room with a loud speaker in it. several times longer than the It is doubtful whether any one The latter is connected up to play slowest vibrations used in regular :ould learn the code just by listen- the music for the crowd, but the radio communication. ing to the clicking in a hundred master of ceremonies has a tele- There does not seem to be any :ears and furthermore it is going phone head set which he wears very substantial reason for sup- in English, a language which you Ind which he can plug in at an posing that these waves came ':now. All the detective stories of instant's notice on the detector from Mars-it appears something leciphering a code have assumed or first step, so as to cut off the like the argument of the fellow that the detective knew the lan- music from the loud speaker. Of who knew he muet be listening to ;uage in which the code was writ- ..ourse, there are some sets which San Francisco because the words ten. If you were so lucky as to are not provided with more than sounded like Chinese. It has not guess the meaning of dots and one jack, and in such a case it is even been proved that the vibra- dashes, would you be able to read considerably more bother to work tions can come from outside the a message coming through which the scheme than where there are earth and even if they did it is a was written, say in Russian? And two or more of these units pro- far cry to Mars. The idea seems then, how about its being written vided. However, it can be done to have taken the popular mind in Martian? (if that is what they even in that case. because naturally there is so much speak on Mars). The operator, . with his phones curiosity about what is going on As a final point, even assuming on, tunes in to some station. He hi our neighboring planet. that we could get to the point need not know what it is, but he Frankly, we very much doubt where we understood what they must adjust the set until music whether these signals had any were saying and could talk back comes in good and clear, then he such origin, and furthermore, it 1,nd forth, what messages would pulls out his phones and so lets seems very unlikely that the earth we send? After a few months' the music fill the room through will ever get into communication description of the place it would the loud speaker. The piece is al- with 31 a rs. Pirst of all there is simmer down to the question, lowed to continue until it gets to I1w praet icaally impossible problem -How is the weather up there?" the end and the announcer starts of getting radio waves out into On the whole, we do not feel very making his little speech. Just at space in any chianti ty. If we all much excited about messages from that instant when he says, "This have the greatest trouble in get- Ma rs. is Station " the operator ting England, (except the liars), plugs in his phones, so that the which is only a. few thousand TWO RADIO GAMES company does not hear what sta- miles away, we shall have to go HEN you talk about "play tion it is, but he gets it himself. sUynte Io pick up a place a few hun- ing the game" it often The guests are all provided with dred million Wailes away. The au cans sticking with the thing un- slips of paper, which have num- ra;.Iio waves as we know follow til it is done and being fair about bers down the side and they each along the surface of the earth it. In this case, however, we are write on their slips the call letters and do nol (lad out into space. referring to two radio amuse- ind city which they think fits the Resides this, there is the very ments, which have been proven -tation they have just been listen- practical difficulty of translating rather popular at social gather- ing to. 24 RADIO PROGRESS OCTOBER 1, 1924

Of course, the operator makes of this the radio fans who are on name of the station, because some a note on his slip of the cor- the air very much of the time seem broadcasters do not give out this rect answer, which he has just to be able to tell them right away. information oftener than once in heard. In case the piece was too It is, of course, the announcers every fifteen minutes, but as soon short, or for any other reason, the rather than the individual artists as the music becomes clear, the saine station may be allowed to who are recognized as one singer dials are jogged (the readings are play a second time before tuning may give a concert from several written down on a piece of paper) to a new one. When satisfied that different stations. and such a station counts one a new one is wanted the man at The Tuning Game toward the final score. The host the radio set tunes to another The second entertainment, which usually acts as referee to decide broadcaster with his phones and is sometimes had with a radio set, when the reception is good, or, if again throws it on the loud is different from the first in preferred, the whole company can speaker that to be guessed. This con- it is not suitable for so large a act in this way. tinues until the company have had crowd and that it requires greater It is surprising 'how different enough, when the slips are col- knowledge of radio than the one various people are in lected their ability and compared with the just mentioned. It is played like to get sharp tuning quickly. Some true list, which was made out by this: Each person in turn is seem to have the knack the natural man with the phones. given a certain length of time at and are able to pick up one station It is surprising how quickly the dials of the radio set; five or after another and make them some of the more popular an- ten minutes is the usual length, de- sound well, while others do not nouncers are recognized by the pending on the number of players. seem to get beyond the local broad- listeners. The various broadcast- In his five minutes the player tries caster with any real clearness. ing companies have naturally to see how many different stations The next time you have a party picked out men with personality he can bring in clearly. at home you will find your guests in their voices to occupy such It is not fair to require that he are interested in one or both of responsible positions, and because wait for the announcer to tell the niese radio games. CUTTING DOWN LOSSES another and other objects. Run them crowd everything together. A Phord Continued from Page 18 at right angles when crossing, and try will take you as far as a Phierce Har- amount of radio frequency current pass- to keep them short. Keep a distance of row, but they who can afford it have ing through, Ct will depend on the set- two inches between separate parts in a the latter. ting of the dial. When the capacity set. Use as small amount of spaghetti If a real low loss efficient tuner is is small, only a small amount of high as you can get along with. When two desired, all hints should be carried out. frequency can flow through condenser Ct, wires come quite close together and there It will be of no use to substitute a good and this will reduce the amount of re- is some danger of their short circuiting, coil or condenser in a poor set because generation. When Ct is turned up, it then spaghetti may be used, but it should the set will still be poor even if it has allows a large amount of radio frequency not be put on insulated wires just for one good part. Only a little poison is to flow through it, and this gives a large looks. needed to kill a man. But when these amount of feedback. Conclusion suggestions are carried out, a big im- If the plate bypass condenser Ob To sum it all up-use the best parts provement will be noticed in long dis- (Fig. 4) is across the B battery, it your pocketbook can afford and do not tance reception. should not be a paper condenser as it may leak and might even "blow" or short circuit. Use a mica or other well con- Fone Fun For Fans structed condenser. Howliag is often Those Candid Friends A Minnow for the Reader due to excessive plate inductance. To The Author (posing)-When I write Fair Patient-Oh, doctor, what do you remedy, make the tickler smaller as pre- far into the night I find great difficulty recommend for a tired, fagged -out brain? viously mentioned. Excessive tuned cir- in getting to sleep. Doctor-Well, fish is a great brain cuit resistance causes the set to go in The Friend-Then why don't you read food. and out of oscillation with a "plop." The over what you've written?-Klods Hans Patient-What kind of fish? remedy is to use low loss condensers and (Christiana.) Doctor-Why, for you, a couple of coils. Incorrect grid leak adjustment whales might be about right to start may also cause a howl. The remedy here Poor Kids with. Brown Jug. is obvious. Mrs. Dee-"Are you all settled in your Odds and Ends new home ?" Good Sets Wooden panels are satisfactory if dry, Mrs. Kolbrooke-"All but the chil- Customer-"But if you are selling but condensers on the panel should be dren. They can't sleep a wink. My hus- these radios under cost price, where connected so that the filament end is band hasn't had time yet to connect the does your profit come in ?" connected to the panel. Keep the wires aerial for the bedtime stories."-Two Assistant-"We make our profit out separated as far as possible from one Bells (Georgia.) . of repairing them."-London Opinion. OCTOBER 1, 1924 RADIO PROGRESS 25

ake a Good Cabinet for Your Radio Radio Woodworking for the Wireless Fan

By W. S. STANDIFORD

LARGE numbers of amateur radio to have the ends of all boards cut as having its advantages and disadvantages. fans throughout the United States squarely as possible. At the outset, be- Soft woods like pine, are easier to work and Canada are constructing their own fore any work is started, assemble your than the harder varieties such as oak, sets to "listen -in" to broadcast programs. set in position on a table and measure but a case constructed of the latter will Most of their instruments are very good its width, length and height; allow suf- be far stronger than one made out of ones and work well when used the first ficient wood to project on all sides so as pine wood. On the other hand, soft few times, until the spaces between the to prevent the instruments of your radio woods (which are close -grained) require leaves of their variable condensers, jacks outfit from touching the inside parts of less work to be done on them in the final and other parts of the outfits clog up the case. It is much better to have varnishing operations, and furthermore, with dust. Then *trouble occurs. It is plenty of room for the devices in your they can be made to imitate the more of the utmost importance to the working container than to make one having just, costly woods. of receiving and broadcasting sets that barely enough space to house them. a clear path for the electrical energy In these days of frequent changes of Cutting Groove in Posts (which at its best is very weak, owing radio receiver designs, the advantage of By using pine or poplar, a radio cabi- to distances traveled) should be pro- having a sufficiently large sized box net can be constructed which will look as vided, so that no buzzing sounds due to will, in many cases, render unnecessary if an expensive natural -colored wood accumulated dust, are heard along with the construction of extra ones with their were used, it also being cheaper to make the signals. additional expense. of construction, as than a hardwood one. In the construc- In order to make their apparatus give all that the radio enthusiast has to do tion work, a choice of two methods can the least amount of trouble, manufac- is to disconnect the parts from its in- turers of radio sets enclose them in terior and lift out the panel which holds wooden cabinets. This not only adds to the other instruments, and then slide in their appearance, but increases their to the box's grooves, a bakelite or hard efficiency. In sharp contrast to this, rubber panel having its holes cut to con- many fans do not enclose their outfits in form to the desired pattern. a case but try to keep dust away from the delicate parts by frequent cleaning, Panel Held Without Screws a process that not only wastes time, will be observed the method of It that Fig. 1. Striking Appearance Shown but is likely to press some wire connec- holding the panel in this style of con- tions shape, too close together or out of struction is different from that of the be adopted, both producing good results. thus causing other difficulties during usual course adopted; that is, of using All grooves in the four end posts can be operation. brass screws to secure it in place. The either cut in by the amateur woodworker Home Made Cabinets Crude panel slides in grooves, and depends upon with the aid of a tongue-and-groover As a general rule, most radio fans the weight of the panel and its attached plane (which can be bought at any hard- who do construct their own wooden cab- appliances, also the friction between ware store) or he can have this work inets, fail to make neat -looking ones tight fitting panel and its grooves to done at a planing mill and thus save a re- through a lack of knowledge of the pro- hold it down solid. This not only lot of work. cesses and tools needed to do a good job, sults in ease of removal but a very fine Supposing that the latter course is rather than because of any carelessness looking box with sharp corners. The ap- adopted, proceed as follows: The tools in this work. The weak point where pearance of the cabinet is shown in needed will be a block plane, saw, small most amateurs fall down in carpentry Figure 1. The use of four square posts, hand drill, stock, and also a 1/16 inch work is in making neat -looking joints; one on each corner, gives additional diameter drill to fit the stock, brad awl, the result being that the box looks crude strength and makes a rigid container, a square having a 12 inch blade, vise, when it is finished. By constructing the one which will hold the apparatus in its and a cheap wooden mitre -box. The lat- joints of your wooden container on the interior without any bending of the box ter will not be needed if the constructor lifted up. plan outlined in this article, a fine - when it is can saw to straight lines. A piece of appearing cabinet will be the result. But The first thing to do is to decide what sandpaper tacked on a. block of wood care must be taken to cut all grooves in kind of wood your box is to be made of, can be used for squaring the sides at the end posts to an even depth, and also whether of soft or hardwood; each class right angles to one another, although, 26 RADIO PROGRESS OCTOB1t 1, 1924

it will take more time in construction being taken from the outside corner of work to remain inseparable. In con- Other needs are screwdriver, 2 -dozen one post to another. This makes a neater struction work on radio cabinets of this flat head brass wood screws (don't use looking box. Details of construction type it is advisable to glue the longest iren or steel ones in radio work as they show in Figure 2. section first. The ends of the boards may interfere with reception), about 7/8 Make your top cover the same size as should make a driving fit into all post inch long, also two wood screws 11/4 the bottom in regard to length and slots. Taking one post of the back sec- inches long, a can of liquid glue and suf- width, but use h -inch lumber instead tion, lay it with its slot facing upwards; ficient wood having a thickness /g of inch of 1/s -inch thick stuff. Having the wood then put some glue into the groove and after planing, to make the sides and top planed smooth and cut to the desired also on the end of your board that is to of your container. Make the wooden size, we are now ready for glueing it go into it. base out of 1/2 inch thick stock, as this together. All wooden sides should be Put them together by placing one end imparts greater strength and stiffness made to fit rather tightly (but not too of the board in the slot, then lay a block than a inch / board. firmly, as splitting may occur) into the of wood on the other end and hammer If a set is over 18 inches long, a hard- slots where they are designed to go. A it down in position; take care to see that wood baseboard can be used; in fact, few remarks about the amount of glue the bottom of the groove and the end hardwood makes an excellent bottom for used on the joints will not be out of of the board are in contact. Wipe off any radio outfit. The square slotted place, as success or failure depends, to any surplus glue that exudes out and posts that form the right and left cor - a large extent, upon how it is done. fasten the other end post in the same way. Next lay your board with its posts down upon a level surface, placing a thick plank over the two end posts, ...=L_ , ,:, ir,I., '^ k ',.r weighting it down and leaving until dry. How to Prevent Warping This weighting down prevents any warping taking place due to moisture in the glue while the wood is drying. It also keeps the sides of posts and the board's end at right angles to each other, thus making them dry in that position. After the glue has set, fasten both right and left sides of your box in the same way, hammering with blocks placed on the front posts. It will be necessary to put a board (which is not to be glued) having the exact length of the panel, into the latter's slot; this is to keep the short ends of the box from collapsing Fig. 2. Plan of Cabinet with Panel inward until your cabinet is finished and screwed ners should have their grooves planed Hardwood requires different treatment upon its base. After the two front posts out, while the wood is in one long strip, from the softer varieties. The liquid are glued, turn the rectangular frame over, having two posts they being afterward cut to their re- glue should have a consistency of thick the front facing downwards. The quired length. In using one of these cream; if too thick or strong, dip the short ends should Le pieces for the right-hand side back cor- bottle in warm water or place near the tied together tightly with strong cord so as to make ner post it will be necessary to turn the fire, thinning if necessary with a few them press firmly against wood over, bottom side up, thus making drops of strong vinegar. the board in the panel slot. This pre- vents one slotted face to the left. The right the end sections from spreading before side front corner section should be re- How to Glue the Parts the glue has set. Now rest your versed in a similar manner. Parts made of hardwood which is not thick board (bottom) on top of rectan- very porous, need one thin coat applied gle turned upside down, and weight it How to Save Time on to edges to be united. Let it dry for down without glueing.. It will readily be seen that by this five minutes, then press the wooden side When the glue on the sides has set, method of making the grooves a saving and post firmly into contact. Porous remove the weights, take off the base- of time is effected, for otherwise each lumber, such as soft wood, requires one board and turn it over so as to have its small post after cutting to the correct or two thin coats on each joint to fill top face upward. Then lay the frame height would need its slots cut in on up their pores. In about 10 or 15 min- on it, and after seeing that the margins different sides separately, a tedious job utes after all glue -has been absorbed, of the base are spaced equally from all when done on small pieces. Have the base apply another thin coat and press the sides, weight the frame down to prevent of sufficient length and width so as to sections into position, allowing them to moving out of place; take a sharp extend 1/4 inch over all the way around dry for at least 24 hours. Keep all pointed pencil and mark lines on the (1/2 inch longer over all) , measurements traces of grease away if you expect your Continued on Page 27 OCTOBER 1, 1924 RADIO PROGRESS 27 American Radio Relay League

AIRSHIP TALKS TO LEAGUE Navy Recognizes the Amateurs American amateur wins the transmission Desiring to test out, the new short The navy has been interested in short honors by 500 miles. wave transmitter on the big navy airship wave transmission for some time, and The new record was made during the 'Shenandoah while it is in flight, navy the present incident is another example transpacific tests arranged by the officials have requested the American of the co-operation between navy officials American Radio League for communica- Radio Relay League to have amateur and the amateur organization in this tion between amateur operators of the radio telegraph operators stand a twenty- particular field of radio work. Ama- United States and Canada with those in four hour watch while the big craft is teurs are the recognized leaders in short Australia and New Zealand. Magner passing over the western part of the wave radio transmission. has been informed that he wins the Aus- country from Fort Worth to Seattle by Immediate preparations are being tralian boomerang offered to the first A. R. R. L. to have amateurs to es- way of San Diego. October' 3rd was the made by the radio amateur of North America route west of Forth Worth on Australia. date set for the start of the transconti- along the tablish communication with data nental trip. duty. The wave lengths and other K. L. Riedman of 243 Euclid avenue, are being supplied them. At least three between the navy de- Long Beach, operator of amateur radio The arrangement qualified amateurs in each State that A. R. R. L. called for station 6CGW, was notified of the gift partment and the the airship passes over will be held which of a pair of green suspenders as a con- at least six daily schedules during responsible for communication with her. amateurs will be practically the only solation prize. Riedman exchanged mes- A correspondent of the Associated Press operator means of communication that the airship sages with the New Zealand who is to be on board will send his news local ama- will have with navy officials and the about half an hour after the dispatches by way of these amateurs. broke the public. Both official messages and press teur made the contact that All was accom- dispatches will be received and for- WINS BOOMERANG BY 500 record. communication between 12:20 and 2:20 a. m. warded by amateurs. MILES plished The short-wave set was added to the The world's record for amateur radio Amateurs in this country have been Shenandoah's radio equipment because long-distance two-way communication trying to beat the South American storage batteries are the only source of was captured from a South American record ever since Braggio announced that radio power, and the short-wave trans- operator when W. B. Magner of 464 he had "worked" Ivan O'Meara of Gis - mitter requires less energy for its opera- Sixth street, San Pedro, Cal., made con- borne, New Zealand. This happened on tion and is regarded as being of greater tact with Frank D. Bell of Waihemo, May 22 of this year during the Pan- re- practical efficiency. The government New Zealand, a total distance of 6,900 American amateur tests and was stations are not equipped at present to air miles. The previous world's record garded as especially remarkable on ac- made by the Andes operate on short wave, but the amateurs established by Carlos Braggio of Bernal, count of the barrier are highly skilled in their use. Argentina, was 6,400 miles. The North mountains. , to where the of dark colored canton flannel with its A GOOD CABINET tersunk on the reverse side centering lines were drawn. This is done woolly side facing outward is to be glued Continued from Page 26 to keep all screw heads flush with the on the bottom of the box to avoid not to move bottom board, taking care level of the bottom of the cabinet, which scratching any polished surface. the sides of the frame out of position. will prevent marring any polished sur- outside of Mark around inside and face upon which your container is placed. Screwing on Cover on the frame. By having pencil lines We are now ready to fasten the bottom inside and Make a cover of the same width and bottom board drawn on both of the box to its sides, which is easily con- length as the base, but 3/16 inch thick outside of the frame it enables the accomplished by means of the screws. hold instead of inch. The cover may structor to have all screws (which Then remove the board from the panel / be held in place by four screws, one on the bottom to the sides) spaced at equal slots and also all cords from the sides of the wood, each corner. By having a cover which distances and in the center of the frame, as they are not needed now. is screwed down after the instruments are thus avoiding splitting. Get from any grocery store a piece of adjusted and inside of the cabinet, all thin wood about 3/16 inch thick. Boxes Putting in the Screws dust is effectually kept out. Most peo- Remove the frame, then bore holes for that contain oranges usually have sides a narrow ple prefer hinges, however, which allow your flat head wood screws in the base- of the above thickness. Cut easy inspection of tubes. It is now ready board, spacing all holes about two inches strip about inch wide and of sufficient / a good fit when for varnishing, which can be done by apart on the back and sides of the box. length so as to make the. box. Glue using any good varnish or a combined These holes are bored from the marked placed lengthwise inside of outside work side, down. The bottom part facing the it into place with its straight varnish stain as preferred. If all sides of both front posts which holds the panel should surface flush with the inner is carefully done a most unusual and The of this strip h radio cabinet dif- be secured with 114 -inch flat head brass panel slots. object attractive appearing run of boxes will wood screws. All others are / inch long. to help keep the panel with its instru- fering from the usual Ali screw holes are to be slightly coun- ments in an upright position. A piece be the result. 8 RADIO PROGRESS tcrofKicK 1, 11r_! Sending Station Stories WHEN ICEBERGS SINK go under, but he had actually seen them MacMillan peered user the edge and WHEN Explorer MacMillan was re- at the bottom. MacMillan saw that fur- sure enough he saw au iceberg resting turning from the frozen North to ther argument was useless and demanded solidly on the bottom. The fisherman the town of \\-iscasset, Maine, recently, he proof. grinned triumphantly as they headed the got his radio going some time before he This was what the fisherman had been boat lack to shore. MacMillan paid the arrived and the stories which flew over looking for, but first he wanted to work wager like the sportsman that he is, but the air to the listeners in his home town up a little more interest in the matter by did not have the heart to say that iu were very interesting. making it the subject of a wager. Mac- Ile center of the ice he bad seen bould- For instance, a he told of a Newfound- Millan finally agreed that he would stand er mcighiug many tuns. land fisherman, who almost convinced the treat if the other would point out a real famous Arctic explorer that icebergs honest iceberg, in a place where ice is ROUTING OUT THE FIRE drifting from the far north finally be- never found, at the bottom of the sea. come water logged and, with CHIEF much bub- A little sail boat was by the shore and bling, disappear A radio message broadcast by Station below the surface. the explorer was invited to step inside. The explorer insisted ice, WBZ at Springfield, Mass., fooled a fire that whether The wind took the sail and, in a short it be frozen in the shape chief completely when he tried to get of a great berg, time, the voyagers were several miles or just a plain cake, away from everything fur a fea weeks will always float, out from land. "Now then," said the but the fisherman and to avoid all means of communica- was equally insistent fisherman, " look down there and tell me tion with the busy outside world. drat lie had not only watched the bergs uhat you see." "1 thought I had succeeded in getting away from everybody and was at the tail end of the earth," describes the con- NOW TOMORROW MO HJNG fidence of the subject of our story. But YOU LISTEN IN FROM 9 TO a flash by radio, a description of the person, the help of co-operative citizens, s1 l I.30 -THAT'LL FIX short tie-overs by telephone THAT COLD IN `4OU = and train to HEAD AND -tT-.- fill in gaps in the line of communication, canoe trips, portages and tramping through miles of untracked forests-all these were necessary to the delivery of the call of duty. John C. Moran, Chief of the Fire De- partment of Hartford, Conn., is the gentleman whose vacation plans were spoiled by the WBZ radio message. But the call to duty was urgent. The assist- ant fire chief had died suddenly and the Hartford Fire Department was without a leader. Chief Moran had left on hunting trip in the northern Canadian woods, 200 miles north of Quebec.

Precisely "How would you classify a telephone BROADCAST BILL CURES A COLD girl? Is hers a business or a profes- The latest thing in radio And that is why the radio sion ?" Is how to cure a cold. Will help you every day. "Neither. It's a calling!" --Loudon It is the way, the doctors, say, It's good for warts, and other sorts Mail. To stop from getting old. Of trouble, doctors say.

And so next time you're feeling sick, Mailing Lists The music starts activities Will help `{uu increase aaka Just do like Broadcast Bill- b«al fur lea rstaas « al...4 ,, Of our lymphatic sua .rt.- . vo th.webuu of cis.unaA glands; nam.,.r roux tot w .,..ttu..,- togs Put on your phones-'twill stop your Natk,u.I, Etat..,,, ..as -lnndi The glands begin, when listening in nab.nahe Y t..-t,.a,, b,..f..wa U, n,eroa. groans C'Y [Guaranteed C ç To orchestras and bands. And cure you when you're ill. 9 io by refund of J cacti -By Del. NOTE: In this section the Technical Editor will answer of special interest to the questioner alone, or if a personal questions of general interest on any radio matter. Any of answer is desired, a charge of fifty cents will be made for our readers may ask not more than two questions, and if each answer. This will entitle the questioner to a personal the subjects are of importance to most radio fans they will answer by letter. However, if the question requires consid- be answered free of charge. in the magazine. If they are erable experimental work, higher rates will be charged.

Question. In building the Rice Neu- to the grid. Pushing in on this handle does not depend on the location of this trodyne described in your issue of separates the two circuits far enough unit. As far as operating the set is con- August 1, I have difficulty in getting apart so that the amount of feedback is cerned, it makes no difference in which the higher wave lengths. 470 meters greatly reduced. This is a simple way place the "C" battery goes. However, it seems to be about the upper limit. How of controlling the tickler action, al- is better to put this device right next can this be raised? though personally we prefer to turn a to the "A" battery and connect it to the Answer. Most of the sets constructed, handle rather than to push and pull it. tube through the coil. The coil referred according to the data given on this neu- to is the tuning coil, if a detector is trodyne, have been able to reach about being connected, or the secondary of 500 meters. In your case it must be Question. I have seen advertised a the radio or audio transformer, if an either that your condensers have not quite lamp used as a loud speaker. What is ampli- fier is meant. These coils, of as large a capacity as those tested out, the advantage? course, are in the circuit anyway, whether or else, owing to the spacing of the wires the "C" Answer. There is no particular ad- battery is used or not. This or the size of the coils, they have location has vantage in this construction, except as a one considerable advantage. not as much inductance as other coils. It puts the matter of looks and convenience. Some "C" battery at ground In either case you can increase the potential as far people think that a loud speaker horn as the high frequency wave length of the set in one of two current is is rather ugly, and by concealing it in concerned. This is because ways-substitute a 15 or 17 plate con- it is con- the form of a lamp it improves the ap- nected directly to the "A" denser for the 11 plate recommended, battery, which pearance. Of course, it also avoids an- is grounded. or else wind ten additional turns It also allows a short grid other large device which would other- lead direct from the (five on each end) on the secondary coil. coil to the tube. wise have to be put on the table with When it is located next to the radio set. As far as the electrical the tube, a Question. In the July 1 issue of RADIO short direct grid lead can no longer and sound characteristics are concerned, be PROGRESS the article, "Regeneration and used, as the wire runs from the there is no difference at all, except that trans- Reflex," did not explain how regenera- former to the "C" battery perhaps the electric light wires running and from tion occurred. there to the grid, instead through the lamp might possibly cause of going direct, Answer. This particular part of the and of course this puts the "C" battery a slight amount of hum in the radio set operation of the set is controlled by at high potential as regards the nearby. However, it is doubtful whether alter- handle 3, which slides coil 3 back and ating current. The alternating current this would be a serious matter. forth. When the handle is pulled out, referred to is the radio frequency, if it it brings this coil close up against coil Question. Some hook-ups I have seen is a radio amplifier, or the audio fre- 9, which is the stator of the variocoupler, recently have shown a "C" battery right quency, if it is used after waves have leading to the detector. When handle 3 next to the grid of the vacuum tube and gone through the detector. Wherever is pushed in, it separates these two coils. some in the same circuit, but near the you see a hook-up with the "C" battery When they are close together the "A" battery. Why is this difference next to the grid, you will know that the energy received from the plate, through made? author has not considered the fine points coil 3, is fed back by magnetic action Answer. A "C" battery is always con- of radio building. In such a case just into coil 9, which impresses it on the nected to the grid. The positive pole take it out of that position and insert it grid. This is like the action in any or- runs 'to the "A" battery and the negative next to the "A" battery. dinary tickler coil regeneration except to the grid. that most sets use a turning coil rather Question. What is the advantage of than a sliding one to control the amount The bias voltage, which is the pres- making the jars of glass in a storage of energy transferred from the plate back sure which this battery gives to the grid, "B" battery? 30 RADIO PROGRESS OCTOBER 1, 1924

Answer. There are two reasons for str.ucted in this way. Such devices should versed it will give a voltage as shown the use of this material. One is that it be avoided. by the dotted lines. Either allows inspection of the plates inside the of these Question. Which are better, brass will charge a storage battery quite cell, and so it can be determined whether rapid- bakelite, or sockets, for vacuum tubes? ly. Such a device is called they seem in good condition or not. The a half -way Answer. These brass sockets have rectifier, because that is all other reason is that while glass is just that reaches bases of porcelain or moulded composi- the storage battery. The other half as good material as hard rubber or wave tion. If the moulded composition hap- is not used, but' it does not moulded compositions for the purpose, register on pens to be bakelite or its equivalent, then your metér, and so you do not still it is a great deal cheaper than the have to no losses will be experienced at this pay for it. It will, however, take latter, and it is also easy to mould. Some twice point. But if it is of some of the cheap as long to charge a battery with of the newer storage "B" batteries are a bulb materials, which have sometimes appear- 'which passes two amperes as using a screw thread moulded into the it would ed on the market, then serious losses may if the whole wave could be used. A full top of the glass jar, and the cover screws occur in the base. One test for this is to wave rectifier consists of two parts on to this. Such a construction works each dip the whole socket into boiling water. just like the other, but one having out very well in practice. re- If it does not melt or soften, it is prob- versed leads. Then the voltage supply to Question. How close is it safe to have ably of bakelite or equal, and if so it is the battery is shown by the continuous the adjustable air condensers to the tun- satisfactory. On the other hand, if it line plus the dotted line in Fig. 1. Here ing coils of a detector? softens it is more apt to be the cheap the battery gets the full advantage of Answer. This depends somewhat on composition, which will not be satis- the entire wave, and so it can be charged the relative position of coils and conden- iactory. While this test does not prove in half the time using a given size of the ser. The coil causes an alternating field that it is undesirable, still it is well to bulb. More information on this subject of magnetism or magnetic lines to os- discard such sockets, as there are plenty was given in the article, "Building Your cillate back and forth through the center of good ones on the market at reason- Own Rectifier," in the August 15 issue of the tube on which it is wound. These able prices which will stand the boiling of RADIO PROGRESS. lines of force induce a voltage in any water test. piece of metal which they strike and the As to the brass shell, it has no effect PUTTING PEEP HOLES IN voltage circles round in the same way on the audio frequency amplifiers. When PANELS used for radio frequency or that the) wires do; that is, they spin detector In order to get a smooth hole in the tubes it may have a very around the axis of the tube. If the con- slight capacity panel about an inch in diameter, so that action, as it is denser plates are located in such a posi- assembled so close to the one may see whether the tube is burn- elements inside tion that they lie parallel to the various the tube. If there is any ing properly or not, it has been cus- turns of wire, then there is a great tend- such condenser action it will be unde- tomary to cut the opening with a drill sirable, ency for eddy currents to be formed, although small, and for this and then enlarge this to size with a which reduce the volume of the music reason we usually recommend sockets knife or file. This is a rather slow job, and cut down the selectivity of the set. without the metal shell far radio am- and it is not very easy to get a hole that Such a position would be one where the plifiers. is smooth and round. condenser was mounted right at the Question. What is meant by a "full end of the coil with its shaft in the axis wave" rectifier? of the coil. If it is necessary to have Answer. A rectifier is used only for such a position for these two units then converting alternating current to direct. the spacing between them should be at The electricity which comes into your least three and preferably five of six house from the central station, if alter- inches. nating, consists of a positive loop and then a negative loop. That is, the current In ease the condenser and coil are reverses in direction and runs first in mounted side by side, instead of end for one way and then the other, as is repre- end, it is safe to put them a lot nearer sented in the upper half of Fig. 1. A rec- together, although usually they should tifier works like a valve and suppresses A tool has recently appeared on the not go much closer than one inch or two or cuts out every other loop. It may be market which cuts the hole straight and apart. Eddy currents will not be formed connected so that it passes only the posi- true. First a 3/16 pilot hole is drilled with this location and the only objection tive loop, or by reversing the leads it in the panel right in the center of the to having them too near together is that will suppress the positive lead and leave place where the peep hole is to go. The there will be some loss owing to the only the negative. Referring to the lower pilot or projecting end of the Stevens capaoity between the two. This is not a half Fig. 1. of a rectifier connécted to panel cutter is inserted in it and the very serious matter, however, and it is pass the positive half of each wave would cutter rotated by an ordinary car- not nearly as bad as the eddy current give a curve of voltage like that shown penter's bit stock or brace. The opera- loss just mentioned. In spite of the ser- by the full line. That is, it gives a half tion is very rapid and the resulting hole ious objection to the end -to -end mount- wave of voltage and then nothing at all is true. The tools come in three sizes, ing, you will notice a good many com- for a short time. This is repeated in- inch, 1 inch, and 1i -inch diameters. bined units on the market which are con - definitely. When the connections are re- The 3- inch size sells for 75c. OCTOBER 1, 1924 RADIO PROGRESS 31

UNITED STATES BROADCASTING STATIONS N.L. K.C. W.P. ARRANGED ALPHABETICALLY BY KLX Tribune Publishing Co., Oakland, Cal 508- 590- 500 CALL LETTERS KLZ Reynolds Radio Co., Denver Col 283-1060. 500 Abbreviations: W.L.. wave length in meters; ,K.C., frequencies in n.,\ 1' Grays Harbor Radio Co., Aberdeen, Wash 263-1140- 250 kilocycles; W.P., watt power of station. KNV Radio Supply Co., Los Angeles, Cal 254-1180- 100 W.L. K.C. W.P. h..NX Electric Lighting Supply Lo., Los Angeles, Cal 360- 833- 100 k.OB N. M. C. of Agri. & Mech. Arts, State Coi., N., ó1 36U- 833- 500 KDKA Westinghouse Elec. & Mfg. Co.. East Pittsburgh 326- 920-1000 KUt' Detroit Police Dept., Detroit, Mich 28o-1050- 500 KDPM Westinghouse Elec. & Mfg. Co., Cleveland, 0 270-1110- 250 1KPO Hale Bros., San Francisco, irai 422- 710- 500 KDPT Southern Electrical Co., San Diego, Cal 244-1230- 100 KQV Doubleday -Hill Electric Co., Pittsburgh, Pa 280-1070- 500 KJD Post Dispatch, St. Louis, Mo 545- 550- 500 KDYL Salt Lake Telegram, Salt Lake City, Utah 360- 833- 100 KTW First Presbyterian Church, Seattle, Wash 360- 833- 750 KDYM Savoy Theatre, San Diego, Cal 280-1070- 100 KUO Examiner Printing Co., san francisco, Cal 300- 833- 150 KDYQ Oregon Institute of Technology, Portland, Ore 360- 833- 100 KUh City Dye Works & Laundry Lo., L. Angeles, Cal 360- 833- 100 KWG Portable Wireless Tel. Co., Stockton, Cal 360- 833- 100 KDZB Frank E. Siefert, Bakersfield, Cal 240-1250- 100 KWH Los Angeles Examiner, Los Angeles, Cal Sou- 833- 500 KDZE The Rhodes Co., Seattle, Wash 270-1110- 100 KYQ Electric Shop, Honolulu, Hawaii 288-1040- 100 KDZF Auto. Club of So. Cal., Los Angeles, Cal 278-1080- 500 KYW Westinghouse Elec. & Mfg. Co., Chicago, Ill 535- 560-1000 KZM Preston D. Allen, Oaklana, Cal 360- 833- 100 KFAD McArthur Bros. Mercantile Co., Phoenix, Ariz 360- 833- 100 WAAB Valdemar Jensen, New Orleans, La 268-1120- 100 KFAE State College of Washington, Pullman, Wash 330- 910- 500 WAAC Tulane University, New Orleans, La 360- 833- 100 KFAF Western Radio Corp., Denver, Col 360- 8.33- 500 WAAF Chicago Daily, Drovers Jouinal, Chicago, Ill 286-1050- 200 WAAM I. R. Nelson Co., Newark, N. J 263-1140- 250 KFAJ University of Colorado, Boulder, Col 360- 8.33- 100 WAAW Omaha Grain Exchange, Omaha, Neb 360- 833- 500 KFAQ City of San Jose, San. Jose, Cal 360- 833- 250 WAAZ Hollister -Miller Motor Co., Emporia, Ks 360- 833- 100 KFAR Studio Lighting Service' Co., Hollywood, Cal 280-1070- 150 WABE Young Men's Christian Assn.. Washington, D. C 283-1060-, 100 KFAU Boise High School, Boise, Idaho 270-1110- 150 WABI Bangor Ry. & Elec. Co., Bangor, Me 240-1250- 100 WABL Conn. Agri. College, Storrs, Conn 283-1060- 100 KFBB F. A. Buttrey & Co., Havre, Mont 360- 833- 100 WABM F. E. Doherty Auto. & R'dio E. Co., Saginaw, M 254-1180. 100 KFBK Kimball -Upson Co., Sacramento, Cal 283-1060- 100 WABP *Robert F. Weinig, Dover, Ohio 265-1130- 200 KFCF Frank A. Moore, Walla Walla, Wash 360- 833- 100 WABU Victor Talking Machine Co., Camden, N. J 225-1330- 100 WABX Henry B. Joy, Mount Clemens, Mich 270-1110- 500 KFCL Los Angeles Union Stockyards, Los Angeles, Cal 236-1270- 500 WBAA Purdue University, West Lafayette, Ind 283-1060- 250 KFCM Richmond Radio Shop, Richmond, Cal 360- 833- 100 WBAD Sterling Electric Co.. Minneapolis, Minn 360-' 833- 100 KFCZ Omaha Central High School, Omaha, Neb 259-1160- 100 WBAH The Dayton Co., Minneapolis, Minn 416- 720-1000 WEAK Penn. State Dept. of Police. Harrisburg, Pa 400- 750- 500 KFDH University of Arizona, Tucson, Ariz 360- 833- 150 WBAN Wireless Phone Corp., Paterson, N. J 244-1230- 100 KFDX First Baptist Church, Shreveport, La 360- 833- 100 WBAP Wortham-Carter Pub. Co., Fort Worth, Tex 476- 630- 750 KFDY So. Dakota State College, Brookings, So. Dakota 360- 833- 150 WBAV Erner & Hopkins Co., Columbus, Ohio 423- 710- 500 WBAW Marietta College, Marietta, Ohio 246-1220- 250 KFEL Winner Radio. Corp., Denver, Col 254-1180- 100 WBAY American Tel. & Tel. Co., New York, N. Y 492- 610- 500 KFEQ J. L. Scroggin, oak, Neb 268-1120- 100 WBBG Irving Vermilya, Mattapoisett, Mass 248-1210- 500 KFEX Augsburg Seminary, Minneapolis, Minn 261-1150- 100 WBBM Frank Atlass Produce Co., Lincoln. Ill 255-1330- 200 WBBR Peoples' Pulpit Ass'n, Rossville, N. Y 273-1100- 500 KFFV Graceland College, Lamoni, Iowa 280-1070- 100 WBR Penn State Police, Butler, Pa 286-1050- 250 KFFY Pincus & Murphy, Alexandria, La 275-1090. 100 WBT Southern Radio Corp., Charlotte, N. C 360- 833- 250 KFGC Louisiana State University, Baton Rouge, La 254-1180- 100 WBP City of Chicago, Chicago, Ill 286-1050- 500 WBZ Westinghouse Elec. & Mfg. Co., Springfield, Mass.337- 890-1000 KFGD *Chickasha Rad. & Elec. Co., Chickasha, Okla 248-1210- 100 WCAD St. Lawrence University, Canton, N. Y 280-1070- 250 KFGH Le:and Stanford Jr. Univ., Stanford Univ., Cal 273-1100 500 WCAE Kaufmann & Baer Co., Pittsburgh, Pa 461- 650- 500 KFGJ Mo. Natl. Guard, 138th Infantry, St. Louis, Mo 265-1130- 100 WCAH Entrekin Electric Co., Columbus, O 286-1050- 100 Tex 250-1200- 500 WCAJ Nebraska Wesleyan Univ., Univ. Place, Neb 283-1060- 500 KFGX First Presbyterian Church, Orange, WCAL St. Olaf College. Northfield, Minn 360- 833- 500 KFGZ Emmanuel Missionary Col., Berrien Sprs., Mich 268-1120- 250 WCAP Chesapeake & Potomac Tel. Co., Wash'gt'n, D. C.469- 640- 500 KFHD Utz Electric Shop, St. Joseph, Mo 225-1330- 100 WCAR Alamo Radio Elec. Co., San Antonio, Texas 360- 833- 100 KFHJ Fallon & Co., Santa Barbara, Cal 360- 833- 100 WCAS W. H. Dunwoody Ind. Inst., Minneapolis, Minn 246-1220- 100 S. S. D 240-1250- 100 KFI Earle C. Anthony, Inc., Los Angeles, Cal 469- 640- 500 WCAT Dakota State Sch. of Mines, Rapid City, WCAU Durham & Co., Philadelphia, Pa 286-1050- 250 KFIF Benson Polytechnic Institute, Portland, Ore 360- 833- 100 WCAY *Milwaukee Civic Broad. Assn., Wilwaukee Wis 261-1150- 250 KFIX R. C. of Jesus Christ of L.D. Sts., Ind'p'nd'n'e, Mo.240-1250- 250 WCBC Univ. of Michigan, Ann Arbor, Mich 280-1070- 200 KFIZ Daily C'm'nw'lth & O.A.Heulsm'n, Fond d'L'c,Wis.273-1100- 100 WCBD Wilbur G. Voliva, Zion, Ill 345- 870- 500 WCK Stix, Baer & Fuller Dry Goods Co.. St. Louis, Mo.360- 833- 100 KFJC Seattle Post Intelligencer, Seattle, Wash 270-1110- 100 WCX Detroit Free Press, Detroit, Mich 517- 580- 500 KFJK Delano Radio and Electric Co., Bristow, Okla 234-1280- 100 WDAE Tampa Daily Times, Tampa, Fla 360- 833- 250 KFJM University of N. Dakota, Grand Forks, N. Dak 280-1070- 100 WDAF Kansas City Star, Kansas City, Mo 411- 730- 500 WDAG J. Laurance Martin. Amarillo, Tex 263-1140- 100 KFKB Brinkley -Jones Hospital Association, Milford, Ks 286-1050. 500 WDAH Trinity Methodist Church, El Paso, Texas 268-1120- 100 KFKQ Conway Radio Laboratories, Conway, Ark 250-1340- 100 WDAR Lit Brothers, Philadelphia. Pa 395- 760- 500 KFKX Westinghouse Elec. & Mfg. Co., Hastings, Neb 341- 880-1000 WDATJ Slocum & Kilburn. New Bedford, Mass 360- 833- 100 WDAX 360- 833- 100 100 First National Bank, Centerville, Iowa KFLV *Swedish Evang. Mission Church, Rockford, Ill 229-1310. WDBH Worcester, Mass. 268-1120- 100 KFMQ University of Arkansas, Fayetteville, Ark 263-1140- 100 WDBK M. F. Bros. F., H. & Radio Co., Cleveland. 0 248-1210. 100 KFMX Carleton College, Northfield, Minn 283-1060- 500 WDBR Tremont Temple Baptist Church. Boson. Mass 256-1170. 100 492- 266-1130- 500 WEAF American Tel. & Tel. Co.. New York, N. Y 610- 500 KFNF Henry Field Seed Co., Shenandoah, Iowa WEAR Wichita Board of Trade, Wichita, Kas 280-1070- 100 KFOA The Rhodes Co., Seattle, Wash 454- 660- 500 WEAI Cornell University, Ithaca. N. Y 286-1050- 500 KFPT The Deseret News, Salt Lake City, Utah 360- 833- 500 WEAJ University of S. Dakota, Vermillion, S. Dak 2R3-1060- 200 100 WEAM Borough of N. Plainfield, N. Plainfield, N. J 286-1050- 150 KFQB Search Light Publishing Co., Fort Worth, Tex...-254-1180- WEAN Shepard Co.. Providence. R. I 273-1100- 100 KFQC Kidd Brothers Radio Shop, Taft, Cal 227-1320- 100 WEAO Ohio State University, Columbus, Ohio 360- 833- 500 KFQD Chovin Supply Co., Anchorage, Alaska 280-1070- 100 WEAP Mobile Radio Co., Mobile, Ala 360- 833- 100 KFQU 234-1280- 100 WEAS Hecht Co.. Washington, D. C 360- 833- 100 W. Riker, Holy City, Cal WEAU Davidson Bros. Co., Sioux City, Iowa 275-1090- 100 KFQV Omaha Grain Exchange, Omaha, Neb 231-1300- 100 WEAY Iris Theatre, Houston, Texas 360- 833-, 500 KFQX Alfred M. Hubbard, Seattle, Wash 233-1290- 250 WEB *Benwood Co., St. Louis, Mo 273-1100- 100 III K FQZ *Taft Radio Hollywood, Cal. 240-1250- 250 WEBH Edgewood Beach Hotel Co., Chicago, ..-....-.... Co., WEBJ Third Avenue Rv, Co., New York, N. Y 273-1100- 5'17 KFSG Echo Park Evangelistic Ass'n, Los Angeles, Cal 234-1280- 500 WEBL *R. C. A. United States (portable) 226-1330- 100 KGO General Electric Co., Oakland, Cal 312- 960-1000 WEV Hurlburt Still Electric Co., Houston, Texas 263-1140- 100 Louis, Mo ..280-1070- 100 KGU Marion A. Mulreny, Honolulu, Hawaii 360- 833- 250 WEW St. Louis University, St. WFAA Dallas News & Dallas Journal, Dallas, Tex 476- 630- 500 KGW Portland Morning Oregonian, Portland, Ore 492- 610- 500 WFAB Carl F. Woese, Syracuse, N. Y 234-1280- 100 KHJ Times-Mirror Co., Los Angeles, Cal 395- 760- 500 WFAN *Hutchinson Elec. Service Co., Hutchinson, Minn 286-1050- 100 KHQ Louis Wasmer, Seattle, Wash 360- 833- 100 WFAV Univ. of Nebraska, Dept. of E. Eng., Lincoln, Neb 725-1090- 250 Northwest Radio Service Co., Seattle, Wash 270-1110- 100 WFBG William F. Gable Co., Altoona. Pa. 261-1150- 100 KJS Bible Institute of Los Angeles, Los Angeles, Cal 360- 833- 750 WFBH Concourse Radio Corp., New York, I3'. Y 273-1100- 500 KLS Warner Brothers, Oakland, Cal 360- 833- 250 WFBW Ainsworth -Gates Radio Co., Cincinnati, Ohio 309. 970. 750 RADIO PROGRESS OCTOBER 1, 1924

W.L. W.P. WKY WKY Radio Shop, Oklahoma, Okla WLAG Cutting 833-360- & Wash. Radio Corp., Minneapolis, Minn 416- 0. 500 WLAH Samuel Woodworth, Syracuse, N. Y WLAL 234-1280- 100 Naylor Electrical Co., Tulsa, Okla 360- 833- 100 WLAN Putnam Hardware Co., Houlton, Me WLBL 283-1060. 250 Wisconsin Dept. of Markets, Stevens Pt., Wis 278-1080. WLW Crosley 500 Radio Corp., Cincinnati, 0 423- 710- 500 WMAC Clive B. Meredith, Cazenovia, N. Y WMAF Round 261-1150- 100 Hills Radio Corp., Dartmouth, Mass 360-.833- 500 WMAH General Supply Co., Lincoln, Neb WMAK *Lockport 254-1180- 100 Board of Commerce, Lockport, N'. Y 273-1100- 500 WMAQ Chicago Daily News, Chicago, Ill WMAT Paramount 448- 670- 500 Radio Corp., Duluth, Minn 266-1130- 250 WMAV Alabama Polytechnic Institute, Auburn, Ala WMAY Kingshighway 250-1200- 500 Presbyterian Church, St. Louis, Mo 280-1070- 100 WMAZ Mercer University, Macon, Ga WMC "Commercial 261-1150- 100 Appeal," Memphis, Tenn 504 600- 500 . WMU Doubleday -Hill Elec. Co., Washington, D. C 261-1150- SF1[PCOAll-WAVEJ WNAC Shepard 100 Stores, Boston, Mass 278-1084 100 WNAD University of Oklahoma, Norman, Okla WNAP 360- 833- 100 Wittenberg College, Springfield, Ohio 231-1300- 100 (OUPL.tR WNAT Lenning Brothers Co., Philadelphia, Pa Noi-Radiatin WNAX 360- 833- 250 Dakota Radio Apparatus Co., Yankton, S. D 2441234 100 WNYC 'City of New York, New York, N. Y WOAC 526- 570-1000 elusive Pagan Organ Co., Lima, Ohio 265-1130- 150 nabs those WOAG Apollo Theatre, Belvidere, Ill 273-1104 100 WOAI Southern Equipment Co., San Antonio, Tex 384- 780- WOAL 500 holds ern William E. Woods, Webster Groves, Mo 229-1314 100 and WOAN Vaughn C'nserv't'ry of Music, Lawrenceb'rg, Tenn 360- 833- 200 Stations WOAV Penn. Nat'l Guard, 2d Bat, 112th Inf., Erie, Pa 242-1244 100 WOAW Woodmen of the World, Omaha, Neb 526- 570- 500 Wavelengths from 150 to 1000 meters in single circuit; WOAX Franklyn J. Wolff, Trenton, N. J 240-1254 500 150 to 700 meters in triple circuit-the ba.nkwound and WOC Palmer Sch. of Chiropractic, Davenport, Iowa 484- 620- S00 tapped primary and tapped secondary do the trick. WOI Iowa State College, Ames, Iowa 360- 833- 500 WOO John Wanamaker, Philadelphia, Pa 508- 590- S00 WOQ Six efficient hook-ups At Western Radio Co., Kansas City, Mo 360- 833- 500 all dealers or sent WOR L. Bamberger & Co., Newark, N. J 405- 744 50U with each coupler or prepaid on re- WOS Mo. State Marketing Bureau, Jefferson City, Mo 441- 680- 500 sent for ten cents to WPAB Pennsylvania State College, State College, Pa 283-1060- 300 cover mailing. ceipt of price.. WPAC Donaldson Radio Co., Okmulgee, Okla... 360- 333- 100 WPAH Wisconsin Dept. of Markets, Waupaca, Wis 360- 833- 500 WPAJ New Haven, Conn 268-1124 100 Made and Fully Guaranteed by WPAK North Dakota Agri. Col., Agri. College, N. D 283-1060- 250 WPAL Avery & Loeb Elec. Co., Columbus, Ohio 286-1050- 500 WPAM Auerbach & Geutell, Topeka, Kas 275-1090- 100 SHEPARD-POTTER CO., Inc. WPAZ John R. Koch (Dr.), Charleston, W. Va 273-1100- 100 Dept. 35 WQAA Horace A. Beale, Jr., Parkesburg, Pa 360- 833- 500 P, So. River St. Plattsburgh, N. Y. WQAC E. B. Gish, Amarillo, Tex 2344 280- 100 WQAM Electrical Equipment Co., Miami, Fla 283-1064 100 WQAN Scranton Times, Scranton, Pa 2841070- 100 WQAO Calvary Baptist Church, New York. N. Y 360- 1133- 100 W.L. LC. W.P. WQAQ Abilene Daily Reporter, Abilene, Tex 360- 833- 100 WQAS Prince -Walter WFI Strawbridge & Clothier, Philadelphia, Pa 395- 760- 500 Co., Lowell, Mass 265-1134 100 WGAQ 'Youree Hotel, Shreveport, La WOAX Radio Equipment Co., Peoria, Ill 248-1210. 100 360- 833- 100 Calumet Rainbo Broadcasting WGAY Northwestern Radio Lo., Madison, Wis 364 833- 100 WQJ Co., Chicago, Ill 448- 670- 500 WGAZ South Bend Tribune, South Bend, Ind WRBC Immanuel Lutheran Church, Valparaiso, Ind 278-1080- 500 364 833- 250 WRK Doren Bros. Electric WGI Am. R'dio & Res'ch Corp., Medf'd Hillside, Mass 360- 833- 100 Co., Hamilton, Ohio .360- 833- 200 WGL Thomas F. J. Rowlett, Philadelphia, WRAL No. States Power Co., St. Croix Falls, Wis 248-121')- 100 Pa 360- 833- 250 WRAM Lombard WGN Drake Hotel (Whitestone Co.), Chicago, Ill 370- 810-1000 College, Galesburg, Ill 244-1230- 250 \\'GR *Federal Manufacturing WRAV Antioch College, Yellow Springs, Ohio 242-1240 100 Co., Buffalo, N. Y 319- 940- 750 WRAX Flexon's WGY General Electric Co., Schenectady, N. Y 380- 790-1000 Garage, Gloucester City, N. J 268-1120. 100 WRC Radio Corp. of America, Washington, D. C 469- 640- 500 WHA University of Wisconsin. Madison, Wis 360- 833- S00 WRK Doren WHAA State University of Iowa. Iowa City, Iowa 484- 620- Bros. Electric Co.. Hamilton, Ohio 360- 833- 200 500 WRL Union College, Schenectady, Y WHAD Marquette University, Milwaukee, Wis 2841070- 100 N. 360- 833- 500 WRM University of Illinois, Urbana, Ill 360- 833- 500 WHAG University of Cincinnati, Ohio 222-1354 200 WRW WHAH Rater Supply Co., Joplin, Mo Tarrytown Radio Research Lab., Tarrytown, N. Y 273-1100- 500 283-1060- 250 WSAB S. E. Mo. State T'chers' WHAM University of Rochester, Rochester, N. Y 283-1060- 100 Col., Cape Giradeau, Mo 360- 833- 100 WSAC Clemson Agri. Col., Clemson College, S. WHAS Courier-Journal & Louisville Times, Louisville, Ky 400- 750- 500 C 360- 833- 500 WSAD J. A. Foster Co.. Providence, R. I 261-1150- 100 WHAZ Rensselaer Polytechnic Institute, Troy, N. Y 380- 790- 500 WSAH WHB Sweeney School Co., Kansas City, Mo 411- A. G. Leonard, Jr., Chicago, Ill 248-1210- 500 734 500 WSAI U. S. Playing Card Co., Cincinnati Ohio 309- 970- 500 WHK Radiovex Co., Cleveland, Ohio 283-1064 100 WSAJ Grove George Schubel, New York, N. Y City College, Grove City, Pa 360- 833- 250 WHN 360- 833- 100 WSAP Seventh New York, N. Y 263-1140- WHO Des Moines, Ia. 526- Day Adventist Church, 250 574 500 WSAR Doughty & Welch Elec. Co., Fall River. Mass WIAC Galveston Tribune, Galveston, Tex 360- 833- 100 254..-....-.. Howard R. Miller, Philadelphia, Pa WSAV Clifford W. Vick Radio Const. Co., Houston, Tex 360- 833- 100 WIAD 2541184 100 WSAX Chicago Radio Laboratory, Chicago, Ill 448- 670-1000 WIAK Journal-Stockman Co., Omaha, Neb 278-1080- 250 WSAY Irving Austin, Paducah Evening Sun, Paducah, Ky 360- Port Chester, N. Y 232-1290- 100 WIAR 833- 100 WSB Atlanta Journal, Atlanta, Ga 428- 700- WIAS Home Electric Co., Burlington, Iowa..., 360- 833- 100 500 ..., WSOE 'School of Eng. of Milwaukee, Milwaukee, Wis 246-1220. 100 WIK K. & L. Electric Co., McKeesport, Pa 234-1280- 100 WSY Alabama Brothers, Philadelphia, Pa Power Co., Birmingham, Ala 360- 833- S00 WIP Gimbel 508- 594 S00 WTAB Fall River Daily Herald, Fall River, Mass 248..-....-.. WJAB American Electric Co., Lincoln, Neb 229-1310- 100 WTAC Johnstown, Pa. Jackson's Radio Eng. Laboratories, Waco, Tex 360- 833- 150 275-1090- 150 WJAD WTAM The Willard Storage Battery Co., Cleveland, 0 389- 770-1000 WJAG Norfolk Daily News, Norfolk, Neb 283-1060- 250 WTAN Orndorff Radio Shop, Mattoon, Ill Peoria Star, Peoria, Ill 2841070- 100 240-1254 100 WJAN WTAQ S. H. Van Gorden & Providence, R. I Son, Osseo, Wis 225-1330- 100 WJAR The Outlet Co., 364 833- 500 WTAR Reliance Electric Co., Norfolk, Va 280-1074 100 WTAS Pittsburgh Radio Supply House, Pittsburgh. Pa 286-1050- 500 WTAS Charles E. Erbstein, Elgin, Ill., near 286-1054 Trust Co., Cleveland, Ohio 390- 770- 500 500 WJAX Union WTAT Edison Electric Ilium. Co., Boston, Mass 246-1224 100 WJH Win. P. Boyer Co., Washington, D. C 273-1104 100 WTAW College Station, Texas 280-1070- *R. C. A., New York, N. Y 405- 740- 250 WJY 750 WTAY Oak Leaves Broadcasting Station, Oak Park, íll 283-1330- 500 WJZ Broadcast Central, New York, N. Y 454- 664 500 WTG Kansas State Agri. Col., Manhattan Ks 360- H. F. Paar, Cedar Rapids, Iowa 278-1080- 100 833- 500 WKAA WWAD Wright & Wright, Inc., Philadelphia, Pa 360- 833- 500 W. S. Radio -Supply Co., Wichita Falls, Tex 360- 833- 100 WRAF WWJ Detroit News. Detroit, Mich 517- 580- 500 WKAP Dutee W. Flint, Cranston, R. I 364 833- 250 WWL Loyola University, New Orleans, La 268-1120- WKAQ Radio Corp. of Porto Rico, San Juan, P. R 360- 833- 500 100 WKAR Michigan Agr. College, E. Lansing, Mich I 280-1074 500 WKBF D. W. Flint, Providence, R. I 286- - 500 Changes and additions...... :.,.;.;..;.;,

;%; %;%: JP. .;. . . . . :' i:'% e e . . . . .

ée .O : e.. Radio Dealers! :: : .Ï. .: .:.. .46 Practically every Radio Fan who comes into your store will subscribe to RADIO PROGRESS, if you will keep a few copies on your counter. : Those who won't subscribe will at least buy a single copy.

Why not ring up some of this business on your Cash Register? We will help you and will put you in touch with our distributor in your territory.

You'll be surprised when you discover how big an item this business will amount to in the course of a year. And you take absolutely no risk, nor do you have to invest a single cent of capital.

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Radio Progress

8 Temple Street Providence, R. I.

P. 0. Box 728

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:..;..:-: >e ;..;..;..;..;..;..;..;..;..;..; e.:..;..;..; e ;..;..; e.;..;..;..;. . ;. ;. e : ;.r,..;..;..;..;..;..;..;..;..; .;..;..;..;..;..;..;..: :: ,: RAD I O AIPPAIRA.9rULIN The Giblin Broadcast Receiver

THE Giblin Radio Frequency Broadcast Receiver makes it possible to obtain Q \\\. \ TTP[tL - radio \ STANDARD DAD100ELECTgIC entertainment without the necessity CO. PAWTu CN TR, \ 1, of erecting outside antenna wires or using a troublesome ground wire. A small, loop STABILIZER © © © DETECTOR©\\© aerial placed near the set will pick up sig- "A'SWITtM nals, which, though they have come long AMPLIFIER distances, and are weakened by hills, val- leys, trees and buildings, will be clear and of 2,0 STEP great volume. Many families, living in JED STEP apartments where it is undesirable or im- possible to erect antenna wires, can now hear enjoyable, ever-changing programs through the day and evening by "listening - in" with a Giblin Radio Frequency Broad- The set comprises two stages of radio frequency ampli- cast Receiver. fication, a ,detector and three stages of audio frequency amplification. The parts are mounted on a subbase to which a Bakelite panel is attached. It is enclosed in a handsome solid mahogany cabinet.

TYP` F -- F

AAUU113 APPAtzA?tiS. eikF00ENCY TRANS° Ban.( 230.559 A111 KADIO GELE Nd` KET,141.10121ii5'

The Giblin Audio -Frequency The Giblin Radio -Frequency Amplifying Transformer Amplifying Transformer Price $4.50 Price $5.00

Buy Giblin Products from your dealer Write for descriptive circulars STANDARD RADIO gEILECTRIC Ca PAWTUCIKJE IFe]H[®DIE ISLAND